Car runs like pooh after replacing injectors...

Post by **frenetic** » Wed Oct 07, 2009 2:40 pm

http://www.youtube.com/watch?v=fyN9_plaFs4

It dies when I take my foot off the gas, blows grey smoke, nothing visibly wrong on the engine but I am an idiot about this car. What could I be overlooking?

EDIT: was a improperly seated plenum gasket... I fixed it and now it runs like crap, doesn't spew grey smoke, and whistles a little bit from the same area. Think I screwed up that gasket and need to replace..
Modified by frenetic at 6:26 PM 10/7/2009

Post by **Q451990** » Wed Oct 07, 2009 6:24 pm

That could do it, depending on how much unmetered air is getting in there.

Heath

Post by **frenetic** » Wed Oct 07, 2009 6:28 pm

It still runs like crap though. It's whistling, I am not sure where the whistling is coming from. Hope I can isolate it tomorrow, it seems like a lot of problems for a little air leak.

Post by **Q45tech** » Thu Oct 08, 2009 2:37 am

My first plenum removal was in 1996, the next one was in 2000, then 3 more followed to today.

Failure to replace every hose, every gasket and both KS and harness or all injectors at the same time resulted in EXTRA removals.

Practice makes perfect, especially after hundreds.

Post by **frenetic** » Thu Oct 08, 2009 12:57 pm

I replaced every hose I disconnected or cut, because they were all visibly brittle or cracked.

I only replaced two injectors, because... 200 dollars a piece, well, that is just crap. I replaced gaskets, BUT did not replace the ring gaskets between the plenum and the engine. I was iffy about that, and if I can't identify this problem that's the next thing I will replace. I am no longer fretting removing the plenum because I feel like I can have it apart and all back together in under an hour.

Here's my issue now though, I found a disconnected hose, hooked that up and now it will idle and drive. However, it still makes a high pitched squeal that I cannot pinpoint accurately. It doesn't squeal when I drive it, it squeals sometimes when I rev it, and always squeals when it's idle.

My question is, would a loose injector squeal? It appears to be coming from back near the injectors I replaced, the EGR valve area, etc. I replaced #5 and #7... What can be causing this squeal and what should I look for?

Post by **Q45tech** » Thu Oct 08, 2009 1:22 pm

The make a special inexpensive stethoscope with different types of heads [probes] to pinpoint noises.

Post by **Q451990** » Thu Oct 08, 2009 4:59 pm

Hard to think of anything that would squeal in that area. I think Q45Tech's suggestion of a special stethoscope is a good one. You can get the typical mechanic's stethoscope at Harbor Freight (www.harborfreight.com) really cheap if you have one in your area.

If you think you have a leaking plenum to runner gasket, you can usually track it down by spraying brake parts cleaner around them at idle. If the idle speed goes up you're sucking it in there and the engine is burning it. If you didn't replace them, you should. They are usually rock hard after a few years.

Heath

Post by **frenetic** » Thu Oct 08, 2009 5:04 pm

Q451990 wrote:Hard to think of anything that would squeal in that area. I think Q45Tech's suggestion of a special stethoscope is a good one. You can get the typical mechanic's stethoscope at Harbor Freight (www.harborfreight.com) really cheap if you have one in your area.

If you think you have a leaking plenum to runner gasket, you can usually track it down by spraying brake parts cleaner around them at idle. If the idle speed goes up you're sucking it in there and the engine is burning it. If you didn't replace them, you should. They are usually rock hard after a few years.

Heath

I went after the engine with some carb cleaner while it was idle (something my neighbor recommended) and I found a disconnected hose. It idles now, and I located the squeal. It is my EGR valve, if I pinch the bell or whatever it is called, it goes away. I'll grab one from U-Pull-It tomorrow. It also is acting like it's still misfiring or perhaps has a bad lower o-ring on one of the injectors I replaced. I will get in there tomorrow and let you know...

Post by **frenetic** » Sun Oct 11, 2009 11:19 am

I am officially out of ideas.

Tore the plenum off again, swapped out the o-rings on my injectors, re-seated them nicely... replaced my plenum gaskets, replaced the EGR valve (which I thought was the source of the whistling sound), car still runs rough, throttle appears to stick open when I put my foot on the gas and let go, then slowly comes down. Sometimes it dies after doing this, other times it idles at something like 400RPM, something real low. The exhaust smells like gas (which I was told could be caused by a torn o-ring or improperly seated o-ring)... when the car whistles, if you pinch the EGR valve at the top it stops whistling. Two EGR valves do this now.

Any ideas? I am rapidly running out of money to put into this and would just like to get it back on the road again.

Post by **Infinitiguy19** » Sun Oct 11, 2009 2:43 pm

Did you set the AAC/IACV at ~2.5-3 turns?

Did you replace ALL vacuum hoses?

Did you miss any air hoses (PCV, EGR...)?

Does the exhaust still smell like fuel?

Does the car shake at idle?

Post by **frenetic** » Sun Oct 11, 2009 4:17 pm

Replaced all non-vacuum hoses... and one vacuum hose. I got plenty of vacuum hose left, I'll go ahead and replace each vacuum hose.

I have taken it apart and put it back together 4 times now, I am pretty certain I haven't missed a hose. I have gone after it with carb cleaner to locate any leaks and haven't seen any. It is all back together. The car shakes, mainly cause I think it's at such a low (400RPM) idle.

As for setting the AAC/IACV... no. I wasn't aware of this procedure. I am out of light today, I'll give that a go tomorrow and the hoses as well. Thanks for the ideas!

Edit: you happen to have a link handy for how to adjust the IAC/AAC? I see threads on how to clean it, and all the pictures are dead linked. Anyways I am sure it's fairly obvious once I get in there. I am going to take it off and clean it too, since I had it disconnected from the plenum for about a month.
Modified by frenetic at 7:32 PM 10/11/2009

Post by **Infinitiguy19** » Sun Oct 11, 2009 4:32 pm

Well most vacuum hoses can be replaced with plenum on and throttle body off.

The car shakes because of the bad Air to Fuel ratio at idle. Too much air or too little fuel can cause a stumble. But I am not sure if the idle setting can make the car shake or not.

To set the IACV/AAC (asuming the intake (runners/throttlebody/AAC/EGR and plenum are in near new shape)) Turn the AAC valve to the right as far is it will go (Screw it in all the way) then screw it out till you reach 650 RPM's or what ever you want the car to idle at.

Make sure the AAC/IACV is unplugged and there is no load and use a Laptop Consult or Nissan Consult 1 or 2 to set it, DON'T RELY ON THE DASHBOARD TACHOMETER (As it can be ~200 RPM's off).

Good Luck

Post by **Q451990** » Sun Oct 11, 2009 6:38 pm

Or just set it where it feels right until you get ahold of a Consult or emulator... it's easy enough to redo.

Heath

Post by **frenetic** » Sun Oct 11, 2009 7:05 pm

Q451990 wrote:Or just set it where it feels right until you get ahold of a Consult or emulator... it's easy enough to redo.

Heath

I don't have consult so yes! Still can't see how to adjust the valve, though!

Post by **Infinitiguy19** » Sun Oct 11, 2009 8:10 pm

Look to the left of the valve (Valve cover with oil fill hole) Once there you will see a little philips head screw (You can use a flat head because its easier).

I might make a video of how to do this sometime.

Post by **frenetic** » Mon Oct 12, 2009 10:24 am

I am completely out of ideas now. I replaced the vacuum hoses, swapped out the EGR valve, fiddled with IACV... I am befuddled. I am either the worst mechanic in the world or I have stumbled upon the most fickle Q45 ever.

When I unplug the MAFS, the car idles at 2000rpm and doesn't stutter like when it's plugged in, but the EGR valve still whistles. I have had issues with the MAFS before so I am certain (about 75% so) that the MAFS is causing the low/bad idle. But, that whistling, it's retarded. If I pinch the bell or whatever you call it on the EGR valve, the whistling stops and the cars idle jumps. when it settles back down, it starts whistling again. It also whistles when revving, but only sometimes.

Right now, I am just trying to pinpoint the cause of the whistling... Even looking in the FSM it says to replace the vacuum hoses, especially to the EGR valve.

So as far as I can tell, no one has really had a whistling EGR valve, at least on these Q45's... Google turns up several mentions of whistling EGRs.... nothing has helped so far.

While I hunt for the whistle, I am looking for a MAFS. The Q at the junkyard already is missing it's MAFS, so I don't know what to do about that right now.

Post by **Infinitiguy19** » Mon Oct 12, 2009 11:09 am

When unplugging the MAF the car should still idle the same because the MAF is'nt really used during warm idle.

You have a air leak somewhere though I am sure, Try using a smoke machine to find it. To rule out a vacuum leak you can test for vacuum.

Q45tech wrote:Vacuum Leak TestingThe only place I use is the vacuum line at the fuel pressure regulator ....rear of engine down in valley....hard to get to. We are talking about a Q45 but on most cars this is the best place to get max vacuum. You should use a tee because if you disco the line from regulator the idle fuel pressure will rise by 10 PSI and the injectors will try to flow 13% more which can lower pulse width due to feedback control

7169 Vacuum Leaks and Testing http://www.asashop.org/autoinc/MAY/Tech2tec.htm

7173 A simple vacuum gauge connected [or teed] to the vacuum line feeding the fuel pressure regulator should read 17-18" minimum at idle warm or cold. If you disconnect the vacuum to pressure regulator the fuel rail pressure will increase from 34 PSI to around 44 PSI causing a 13.7% increase in flow the ECU should respond by reducing the idle pulse width from around 2.2 milliseconds to around 1.95 - 2.0 milliseconds. Remember the ECU is designed to maintain a preset idle rpm so more/less air or more/less fuel are all it has to work with.

One thing to look for would be an air or vacuum leak that is getting into the air intake system after the MAF sensor. When the car is warm, the ECU does not enrich the fuel mixture. If air is getting into the system that is not measured by the MAF sensor in the intake, the extra air leans out the mixture. This usually results in poor warm start and idle.

Check to see if there is a loose or cracked vacuum hose or clamp. One way mechanics check for vacuum leaks is to spray a little gas (butane or methane or ?) in various spots and see if the idle RPM goes up and it smoothes out. If so, that indicates that the gas got into the intake system, and that air is sneaking in through that spot.

Have you recently disassembled the intake system or vacuum tubes? If so I would check there first - maybe you forgot to tighten a clamp or replace a vacuum hose. Make sure all vacuum hoses are connected, since this is an easy way to create an air leak in the system. See Q45tech's response to recent inquiry about cold start problems. I don't know if crank angle sensors would show up only in warm start or not. A bad coolant temperature sensor might. I do think it is a good clue when the problem is only when warm and suspect that something is making the mixture too lean. I had exactly those symptoms once when I forgot to reconnect a small vacuum connection.Bob

Here he says

Q45tech wrote:What is idle no AC vacuum should be 22 " What is AACV reading should be 10-15% no AC. Could be some trans aging are you running syn ATF and flush every 30k. Techron [or other cleaners] is not magic one or two bottles won't undo years of neglect resulting in carbon build up on piston crowns or bore tops. Nothing but manual cleaning will remove the EGR crud from the intake system from the throttle body on down to injectors.

So I am a bit confused what the vacuum pressure should be.

If you want you can call me, but email me for my number.

Post by **Q45tech** » Mon Oct 12, 2009 1:04 pm

The idle plenum pressure should be 61 - 68 kilopascals.http://www.cleavebooks.co.uk/scol/ccpress.htm

Post by **frenetic** » Mon Oct 12, 2009 1:20 pm

Thanks for this information. I will find a vacuum tester and check.

I hope this is all one related problem that can be solved with one fix. I have taken this plenum off so many times, disconnected and reconnected hoses etc, I am wondering what it could be.

If I spray carb cleaner down on the right bottom side of the intake manifold where it meets the plenum, it gives the engine a boost. I have taken this off, re-sealed it... It's a brand new gasket and everything. I have focused my search on this area, along with the EGR valve. But the more I read on the EGR valve, it is sounding like something else is causing it to whistle, as in, the EGR valve itself is perfectly fine (both of them I have), but there's something causing air build up somewhere. I have been looking through the FSM for a while now trying to pinpoint this, but I'm still as confused as ever.

I will probably not be able to get a vacuum test done until tomorrow.

Post by **Q451990** » Mon Oct 12, 2009 3:03 pm

frenetic wrote:If I spray carb cleaner down on the right bottom side of the intake manifold where it meets the plenum, it gives the engine a boost.

The fuel pressure regulator is just below that area...

Did you loosen the runers where they bolt to the heads?

You need to continue to look there. If the engine idles faster when you spray carb cleaner there, it is absolutely sucking it in there!

Heath
Modified by Q451990 at 9:33 PM 10/12/2009

Post by **frenetic** » Mon Oct 12, 2009 4:04 pm

Q451990 wrote:
The fuel pressure regulator is just below that area...

Did you loosen the runers where they bolt to the heads?

You need to continue to look there. If the engine idles faster when you spray carb cleaner there, it is absolutely sucking it in there!

Heath

Modified by Q451990 at 9:33 PM 10/12/2009

Just before I lost light for the day, I went out there after thinking about it for a while, what it could be, and I knew the problem must obviously be coming from that area. I cracked off the intake manifold, looked around, and noticed a tear, when I bent the vacuum hose a certain way, on the underside of it. I believe it was the line that runs from the intake manifold to the EGRC solenoid?

I replaced that, started it up, and adjusted my idle. It purrs like a baby kitten now! Still a gassy smell in the exhaust, I will troubleshoot that tomorrow in the daylight, hopefully easier than I did today. I don't feel a miss, the engine runs right, as good as I have ever seen it. I am a little more patient now that I actually have it running.

Thanks for all your help!

Post by **Infinitiguy19** » Mon Oct 12, 2009 4:16 pm

Do you mind taking a picture of the said hose?

Maybe all the vacuum hoses?

Post by **Q45tech** » Mon Oct 12, 2009 4:32 pm

All certified technicans begin as incompetents, after they have done 25-50 plenum jobs they tend to become competent.I can assure you that technicans who have done hundreds still often make simple mistakes UNLESS they replace every single vacuum and coolant hose, bushing and seal at the same time.

We have special exotic names for each hose which cannot be repeated in mixed or immature company..................the Pxssy Hose is a common one.

Post by **frenetic** » Mon Oct 12, 2009 5:01 pm

Paul Wall wrote:Do you mind taking a picture of the said hose?

Maybe all the vacuum hoses?

Sure I will take a couple tomorrow afternoon. It might be hard to get a good picture of that hose though, it's directly under the intake manifold.

I have learned one thing from this: Q45s are never cheap.

Post by **Q451990** » Mon Oct 12, 2009 5:08 pm

That's great news! I know you'll sleep better knowing you found this...

Heath

Post by **frenetic** » Tue Oct 13, 2009 11:55 am

You can see where I cracked open the MAFS a couple months ago to re-solder it

I lost the metal clip for this plug so it is zip-tied.. If I get back to UPullIt I will get another one

The hose that was cracked, and was causing my EGR valve to squeal.

Car runs like pooh after replacing injectors...

Car runs like pooh after replacing injectors...

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