It runs, but rough

[tmorgan4]

I'm making progress in the right direction, but the engine still doesn't run well. It starts up perfect, but runs ROUGH. It shakes like a Harley.

Now that the fuel system seems to be working, I'm convinced my problem is probably either a bad MAF, some cylinders not firing, or a combination of both. A couple days ago I could get it to hold a steady 1990 RPM idle in limp mode with the MAF unplugged, but it still shook the car a lot. After doing some other work (changing the oil, removing and welding up oil pan, installing alternator, etc.) I can't get it to idle on it's own. Whether I have the MAF unplugged or not, I have to keep my foot on the gas to keep it running. Most important part is that is has been throwing a MAF code, but not all the time.

The problem is, I'm not sure whether the rough running could be related to the timing not being set, or something else. Since I haven't been able to get the engine to idle, I haven't been able to time the engine with a timing light (CAS is set in the middle of it's range) or turn off individual cylinders and see if they all cause RPM drops.

Is a MAF code a pretty good sign the MAF is bad? Is there any way to test it before buying a new one? The air flow gauge in Datascan goes up with RPMs like it's working.

[T45]

There is a problem with Q maf's having bad connectors. Read up on it in the Q45 forum. I believe there is a way to fix it or at least troubleshoot it.

If it runs the same with it unplugged and plugged in I would say to start there. My injectors were stuck and that caused my rough idle. Once I unstuck them the engine runs so smooth and quiet now. That noise on my vid is totally gone.

Once you get the maf good I would check all of your injectors to make sure they are pulsing. I think you jimmy'd the pathy harness with the Q ecu so make sure your injector wiring is good. Renting some noids from a parts store is an easy way to check the pulse from the ecu.

I found my bad ones by unplugging the injector harness at the pass side of the engine and taking some jumpers from the battery and found the + and - and just popped each one until I found one with no clicky. I had 2 actually. Even though you had them cleaned they may be stuck from sitting. I doubt it but there's always the chance. One of mine unstuck just by taking it out and the other I had to soak in cleaner and actually force the pintle into action.

The timing is done by the CAS and unless you messed with it the factory specs should be good. If you messed with the setting then you may need to adjust it. Also check tps voltage. You need to make sure your IAC is plumbed into the intake between the MAF and TB. This is mandatory otherwise no idle. I just threw the IAC away and closed all unused ports on the manifold and intake. After that it's just a matter of adjusting the idle stop screw to set your idle. I got rid of the heat pellet idle jazz and all that extra stuff. She runs great even when dead cold.

Don't worry little buddy. You'll be burning them down in no time!!!!!

[craigztoyz]

Have you got the air intake all sealed up, and the iac working, sucking metered air?

A vacum leak is a where I would start, mostly from what you said it is doing.

If you think that it may be a dead cylinder, not an air or timing issue, than pull 1 cyl. at a time, if you pull it, and it stays the same, scope out the electrical on that one cyl. It could have a plugged injector, (i don't know what caused the clogged Reg, guessing could have traveled to an injector)

AH the joys!!!!!!!!!!! soon enough there will be numbers of us, with this same fun. The startup issues. Good Luck,

[tmorgan4]

Thanks again guys. I was convinced it was a bad MAF so I picked a replacement up today and I think it runs smoother, but still very badly. I did however discover something that could cause some of these problems....my #6 lower intake runner is CRACKED. I'm not sure how much that one cylinder would affect the engine running like crap, but I think I should replace it before I make too many assumptions.

More info:The engine has a VERY slow reaction and seems to have a mind of it's own. I will have the throttle body nearly shut and it will rev high, I'll close the TB by hand and it will take a few seconds to go back down. It really takes 3-4 seconds for any input (opening/closing the TB manually) for it to rev up or back down.

IACV tube is hooked up and shouldn't be leaking.

My CAS is 180* off. It was installed right before, but somehow I overlooked it when putting it back in. Does the engine really know which one is firing? If you take the cover off there are 2 marks on the little wheel for #1 cylinder. It's 180* from where it needs to be. Could this be a HUGE issue?

Halfway through a testdrive around the block my brake pedal got hard like when the car isn't running and stayed that way until I shut it off. Weird....

My wideband readings are VERY strange. It will read 22.4 AFR (maximum the gauge will read) nearly all the time while running, but on the "test drive" I'd floor it and while the engine was sputtering it would drop to 7.2 (lowest gauge will read). I calibrated the sensor and all but I'm not sure whether the engine is that messed up or the gauge isn't reading right. It's installed in the driver's side header before the cat.

If you've got any other suggestions, please speak up. My plan now is to pull the plenum yet again, replace the lower #6 runner, test to make sure all injectors are clicking while it's off. If I still have problems afterward I need to check spark on all cylinders as suggested 1000 times.

[tmorgan4]

Quote » I think you jimmy'd the pathy harness with the Q ecu so make sure your injector wiring is good. Renting some noids from a parts store is an easy way to check the pulse from the ecu. [/quote]Never heard of "noids" before but I'll look into them. The injectors did click like crazy when I spun the CAS by hand, but I didn't make sure to check that EVERY injector was clicking.

Quote » timing is done by the CAS and unless you messed with it the factory specs should be good. If you messed with the setting then you may need to adjust it.[/quote]I DID mess with it. Read my comment about my CAS being 180* off above.

Quote »Also check tps voltage. [/quote]

TPS voltage varied with throttle position. I've got it set at about .68-.70 at "idle" with my foot off the gas. Too bad it won't hold an idle there.

Quote »You need to make sure your IAC is plumbed into the intake between the MAF and TB. [/quote]IAC is plumbed into the intake tube after MAF before TB.

Quote »There is a problem with Q maf's having bad connectors. [/quote]I cleaned up my MAF connections and bent the pins to ensure good contact with TWO different MAFs.

[tmorgan4]

Quote »A vacum leak is a where I would start, mostly from what you said it is doing.[/quote]You might be on the right track with this cracked intake runner. Quote »If you think that it may be a dead cylinder, not an air or timing issue, than pull 1 cyl. at a time, if you pull it, and it stays the same, scope out the electrical on that one cyl. It could have a plugged injector, (i don't know what caused the clogged Reg, guessing could have traveled to an injector)[/quote]Should I see a substantrial drop/change in RPM by turning off one firing cylinder? These injectors are all "new" from Deatschwerks so they better not be clogged!

[craigztoyz]

It sounds like you are sucking air from somewhere you are not supposed to(lost brake vac., closed tb, still found air to run, f'd up a/f ratio)You should be able to hear it by the sounds of how severe it is.when pulling intake, look at gaskets, and runners, (don't overtighten,they are aluminum), Get the cas in the right direction if it really is off 180*If you have any doubts on the injectors, get a set of the noid lights(4 in a set, only 1 of the 4 will fit) Yes if you pull 1 plug at a time, it will run even worse if the cylinder was working before you pulled it---- but that is not your problem. All the info you stated above, runs into an air issue, too much to be exact- now where is it coming from is the fun

[draivar]

I have got the exact same issue with my 91...This one will idle but at around 300 rpms. It'll shake and shudder like no tomorrow. However, I do hear what sounds like an air leak under the tbody/tcs extension area...I am troubleshooting this as time permits...Lets keep this thread going folks!!!!

[craigztoyz]

Where is Katy TX?

sounds like you need to use some carb cleaner, and spray it in that area, you should see it suck to a certain area where your leak is. If you did not take things apart, and have a leak, most likely a hose

[draivar]

Its west of houston...sorry to thread jack friend

[tmorgan4]

A small update after another solid week of work on getting this running.........

The #6 runner had a hairline crack on it that ran all the way through it and could be seen from the inside. I had a hard time finding a lower #6 runner and the guy who handles all the fabrication work at the race shop across the street was confident he could weld it up no problem. He welded it up, and resurfaced both top and bottom surfaces to make sure they were flat after welding. I had to improvise a little bit since the runner was now SLIGHTLY shorter than the other 7 but it seemed to seal up really well.

I got 8 new intake gaskets from Infiniti of Scottsdale and can't believe this piece isn't replaced more often. These new gaskets that sit between the lower runners and plenum are SOFT rubber and about twice as thick as the old hard/brittle/shrunken rings that are probably 17 years old.

I broke the CAS installing it when I tried to flip it around. Something I hadn't realized was that it WASN'T on backwards. It can only go on one way. I broke off one of the "ears" that sits inside the cam when I tried letting the bolts pull the CAS in. Bad move, but picked one a new one up today.

I picked up a new MAF and installed that too. Cleaned the connectors well to make sure I'm getting good connectivity.

Got the new CAS installed and timing roughly set up. The engine fires up EVERY time, right away. It still shakes, but seems much smoother than it used to be. It idles nearly perfectly on it's own now at about 800 rpm (guessing there).

More odd symptoms:

I tried driving it, but it still doesn't have enough power to get the Pathfinder back up my driveway.

Since I still have an open exhaust which is dumping right out of the headers, I took a look under there right after shutting it off. One cat was red hot, the other wasn't. Using an infrared gun, the driver's side cat was at almost 600*F, where the passenger cat measured 70*C. I think this is a clear sign that NONE of the passenger side cylinders are firing.

Would it really not have enough power to get up my driveway even if it's running on 4 cylinders? I didn't have my laptop with me to do a "power balance test."

[T45]

Check your injector and coil harnesses. Make sure your coils are getting power and ground and pop your injectors. By popping I mean unplug the harness at the engine, should be on the pass side unless you moved it. When it's unplugged you'll see 2 prongs on the left and 8 other ones on the right. The 2 on the left are power I believe and the 8 other ones are ground to your injectors. This may be vice versa but it doesn't matter for this test. Hook up a jumper to one of the 2 prongs on the left from power. Then take a ground jumper and touch each of the 8 other prongs and listen for the injector click. You should get 4 clicks and then move the power to the other prong and you should get 4 more clicks.

If they all click then turn on your ignition and check power to the 2 power terminals on the opposing plug from ecu and make sure both have juice. I am pretty sure the 2 prongs get power and the 8 others get a ground pulse but I may be wrong. Can't remember.

If all of them click then it's more than likely not injectors. Could be fuel or spark. An easy way to check for fuel is just unplug the fuel line from the drivers side fuel rail after the regulator and fire up the fuel pump. Gas = good. No gas = bad. I think you have your fuel issue solved though but just trying to troubleshoot.

For the coils there are 2 brown/yelllow wires that feed power to the coils IIRC. Make sure all have constant power. If so then ohm all of your coils. The method is in the fsm. IF all ohm correctly then check the coil harness. Mine was brittle as hell but still worked.

[tmorgan4]

Holy s$#%........

I remember reading a thread started by SATAN a while back about his 2,4,6,8 cylinders not firing, and it was because there were 2 identical plugs on the passenger side that can be plugged into the ignitor chip. I decided to go look at it at 4AM hoping that might be my problem.

One quick look confirmed something obvious....the plug was halfway disconnected going into the ignitor chip!!! Plugged it back in, and whatdyaknow....it runs like it should! I'm thrilled right now. There's still a few things that need adjustment, but the damn thing runs like it should (finally).

I drove it around and after I got back to the shop I noticed a light mist of antifreeze all over the engine bay and windshield. I've probably got a little leak somewhere in my radiator or cooling system.

Haven't been this stoked about this project in a long time. Expect a new video tomorrow.

A big thanks to everyone on this board for the help. I'm not done yet, but this is a huge step forward.

[craigztoyz]

SWEET!

I was reading your post of cat temps, and was about to answer that one for ya, but already done. Is it smooth now? if you can post a few pics of the wiring on the motor, that would be helpful, as to where you laid your wires. Thanx

So did you take it out driving at 4:30am? If so How did the neighbors feel about the open pipes in the am? Just joking, been there, moved from there, newer neighbors glad to see me sell the loud toys.

[Mettler]

Remember to put some serious load on the motor every time you take it out from now... the first 20 miles of an engine's life after a fresh rebuild are the most important to ensure the rings bed in nicely! Grats on figuring it out!

[T45]

Any progress T-mo-fo?

[tmorgan4]

Oh yeah...pretty good update here.

I busted up the stock radiator so it was leaking like crazy and holding up the project once again. I didn't want a cheapo parts store replacement if I was going to spend a few hundred dollars on it, I wanted a quality one. I ended up finding a Fluidyne at a local race shop that was almost the exact dimensions I needed. Since it was twice as thick I need to mount an e-fan but it will probably have to be a pusher.

With the new radiator hooked up I got to drive it around about 10 miles and it's driving pretty well. I'm still throwing 4 codes......

A/T signal (duh)EGR temp sensor (duh)Injector circuit (didn't expect that one)Occasionally a MAF code.

The injector circuit code was odd to me. I'll just have to go through the FSM and see if I can track down what's happening.

The MAF code shows up randomly so I think it might be something with the connection.

Something I did learn is that the VH DOES NOT like to be run with the exhaust dumping right out of the manifolds. My wideband was always reading super lean and after talking with a few people I realized it's because the exhaust is so open. I'm assuming the regular O2 sensors are reading super lean too because there's a point (I'm assuming when it goes into the "closed loop" and uses O2 feedback) it shoots STEADY foot long flames out of the exhaust even while idling. All the power would be gone and I'd have to kill it, wait for it too cool down and it would run great again. I'm working on building the exhaust right now.

[Q45tech]

Injector leak code doesn't mean what you think! It is the result of the ecu seeing O2 sensor is going rich excessively.............could just be sluggish old O2 sensor or a cylinder misfiring [plugs/ign etc].

When we bring the dead back to life: new plugs, new O2s, one of our test good MAF, set CAS base advance CORRECTLY.........................the trick is to somehow keep it running until coolant normalizes to 174F and of course MEASURE the fuel pressure at rail input and make sure fuel pressure damper and regulator are new or working properly.

Then do a multiple unstressed and stressed power balance and attack what you've missed.

The 300zxtt/Q45 oem fuel pump equals the Wilboro 255...................the trimode oem pump speed control is a balanced system to avoid stressing the pulse dampener [controlled by vacuum line after MAF 0> 14" H2O at redline] and 34>44 psi pressure reg.

[T45]

Not to threadjack but something caught my attention.

Is the CAS timing procedure like timing with a distributor but with the factory tool/harness plugged in? Have you ever seen a Q with bad timing from just being old? I never messed with my CAS or "CMPS" so it should be at factory setting. If I use my timing light should it be at 15 btdc at idle?

Another thing I need is a fuel gauge. Either that or a dyno day or consult program to make sure all my systems are operating properly.

[T45]

Tmo, I found some cheap fans on a website and am going to order them along with my intake parts. Not sure if you want a good fan or a cheap one but these are the cheapest and look just like the ones summit sells. I am going with 2 12" fans on the Z and being only 30 bucks a piece it fits my budget. I'll be happy if they last a year, then maybe I can afford the big money stuff. Just a thought.

http://www.siliconeintakes.com

EDIT: I take that back. Ebay has the same fans for 30 bucks shipped. You get what you pay for but in my case I'll take it. lol
Modified by T45 at 5:12 PM 3/17/2008

[tmorgan4]

Why hadn't I ever found that website you posted!!!! I just paid $40 each for some fancy Turbonetics 3" to 3.5" couplers!

[craigztoyz]

Oh yeah...pretty good update here.

I busted up the stock radiator so it was leaking like crazy and holding up the project once again. I didn't want a cheapo parts store replacement if I was going to spend a few hundred dollars on it, I wanted a quality one. I ended up finding a Fluidyne at a local race shop that was almost the exact dimensions I needed. Since it was twice as thick I need to mount an e-fan but it will probably have to be a pusher.

With the new radiator hooked up I got to drive it around about 10 miles and it's driving pretty well. I'm still throwing 4 codes......

A/T signal (duh)EGR temp sensor (duh)Injector circuit (didn't expect that one)Occasionally a MAF code.

The injector circuit code was odd to me. I'll just have to go through the FSM and see if I can track down what's happening.

The MAF code shows up randomly so I think it might be something with the connection.

Something I did learn is that the VH DOES NOT like to be run with the exhaust dumping right out of the manifolds. My wideband was always reading super lean and after talking with a few people I realized it's because the exhaust is so open. I'm assuming the regular O2 sensors are reading super lean too because there's a point (I'm assuming when it goes into the "closed loop" and uses O2 feedback) it shoots STEADY foot long flames out of the exhaust even while idling. All the power would be gone and I'd have to kill it, wait for it too cool down and it would run great again. I'm working on building the exhaust right now.

How much exhasut was on it when you took it out on that 10 mile drive? from what it sounds like, nothing past the manifolds, but That can't be the case. Youd be flaming like crazy while driving it.....

[tmorgan4]

All I had was the manifolds for the first 10 miles or so. The flames coming out the exhaust were really odd....it would happen all of a sudden. It would drive great, then I'd lose ALL power while cruising and see in the reflection of buildings and other cars that giant flames were shooting out under the car. I'd just pull over and kill it, wait a few minutes for things to cool off, and it would drive great again for a few minutes.

I got a couple feet of exhaust put on it today and I never ran into this again. The wideband it still reading way off (basically sits at 22.1, goes down to 16:1 or so during full WOT occasionally).

Still fighting a few leaks. I've got one leak that I cannot find out where it's coming from. There's a ton of stuff covered in oil, but I can't even tell whether it's engine oil or power steering fluid.

The idle still isn't steady, and it's a little rough when it's at low RPMs. Sometimes it will try to idle at less than 10000 rpm and it will start to shake pretty badly but normally it's idling at 1500-1800. Once the rpms get up to 2500+ it's really smooth. Maybe something to do with my injector circuit ECU code.

Still got a few issues, but it's running a lot better than it was a week ago.

Anyone know what a good number to keep the coolant temp below? I researched a few things about engine overheating and didn't find a real solid number. The temps start to creep up if I sit idling at a stop light or in the drive-thru at taco bell since I don't have my fan mounted yet.

[T45]

Why hadn't I ever found that website you posted!!!! I just paid $40 each for some fancy Turbonetics 3" to 3.5" couplers!

Ooops, my bad. lol I wouldn't trust them for boost apps but for a NA build they look like good enough quality. At least you'll never have to worry about your couplers being inferior.

Where did you place your wideband sensor at? Got some pics of your final setup so we can see your hosing and stuff?

[T45]

Anyone know what a good number to keep the coolant temp below? I researched a few things about engine overheating and didn't find a real solid number. The temps start to creep up if I sit idling at a stop light or in the drive-thru at taco bell since I don't have my fan mounted yet.

I would guess 220-230 MAX and below would be fine but don't hold me to it. I remember seeing an offroad vid and the driver told the co-pilot that the coolant should read below 260! However they didn't have a VH and were racing baja so I would shoot for 220.

And what the hell are you doing in the Taco Bell drive thru with open headers?

[tmorgan4]

I've got a "decent" exhaust setup on it now. I built one with some 2.5" mandrel bends into a dual 2.5" in 3" out Borla. I'm not sure how much the muffler is even doing at this point since there's no tubing after the muffler. I think it's about as loud as the open headers to be honest.

The wideband got mounted just downstream (literally right next to it) of the factory O2. I just guessed on placement and the wires coming out of the wideband O2 are rubbing on the body. I'll probably have some issues with those wires getting chafed through soon, if they aren't already. I thought it might not be reading right since it was too close to the cat, but it should be getting the same reading as the factory O2.

220-230 sounds about right. I looked in my dad's suburban today and the HOT line is labeled as 260*.

I'm really frusterated once again with this damn oil leak that I cannot find. I've finally figured out that it's engine oil, but where it's coming from, I have NO idea. the entire drivers side of the engine, the steering, the flywheel (since it's open, not good to have oil on the clutch!) the transmission and the gas tank are all covered in oil. I'd assume it's just getting blown back onto everything else, but I can't tell for the life of me where it's coming from. I've had so many problems with this oil pan I may just have to start over with a new one so I'm hoping Jerry might still have the one he was trying to sell.

It still doesn't like idling too well. Sometimes it will idle perfect at 800rpm, but the majority of the time it jumps from 2500 to 2000 then 2500 then 2000 until I get moving again. It's really smooth at higher RPMs.

I'll have to get some pictures when I'm back over there tonight. I didn't want to bring it "home" just yet since it's leaking oil like crazy.

[tmorgan4]

Another step in the right direction........

I started to realize that maybe I shouldn't ignore these codes that keep popping up. They're obviously there for a reason..."Code 51 Injector Circuit" specifically.

Went through and ohmed the injectors through the harness (didn't remove the plenum) and of course, injector #1 is giving me an open (infinity) reading. Checking it out further, the wire got severed when I was installing the plenum. It was cut inside the wiring harness covering and didn't show any damage from the outside. Spliced it back together and the code didn't show back up.

The engine has more power now, but still won't idle perfectly. I think it might be because I've still got a minor vaccum leak between the plenum and #6 lower runner (starter fluid test).

I got a little video showing how it sounds with the Borla. The mic on my computer is pretty crappy, but it sounds OK. The mic seems to pick up some sounds that didn't seem near as bad in person, mainly the belt noise.

There's a sound that I keep hearing when decelerating that I think might be clutch related. It sounds kind of like a metallic ringing/grinding. You can hear it at a couple points in the video. It's not the suspension squeak that shows up a few times.

My new radiator doesn't have a filler cap, or a hookup for an overflow tank. It starts leaking coolant once it heats up since I'm sure it's building some serious pressure since it's got nowhere to go. Don't the Q radiators not have filler caps? Do they have overflow tanks?

http://web.mac.com/t_morgan4/iWeb/Site/VH45.html

[SuperHatch]

My new radiator doesn't have a filler cap, or a hookup for an overflow tank. It starts leaking coolant once it heats up since I'm sure it's building some serious pressure since it's got nowhere to go. Don't the Q radiators not have filler caps? Do they have overflow tanks?

The Q radiators DO have their own caps and a connection to an overflow tank. So in total, the Q has two caps from the factory. One on the filler, and the other on the radiator which also has the little nipple going to the overflow.

[SuperHatch]

P.S. - Sounds great!

[pabs324]

good stuff