Need insight, stuck on a problem.

[cypher02xd]

I have a freshly swapped SR20det into my '91. It's been running pretty good but I've been fighting this issue that I can't seem to track down so I've caved and decided to ask for help. Here's what happening:

Starts up and wants to idle a little low until you tap the gas then the RPM's come up and it will idle ok. It'll intermittenly start to idle roughly than fix itself and run smoothly. When it runs rough it almost sounds like it's cam'd or something, because its a lopey. Now, when I drive it it drives GOOD under 3k rpms and has decent power. In 1st and 2nd gear If I try to accelerate past 3-3500rpms it acts stupid and it bucks, kicks, backfires and just won't do it. in 3rd gear it'll accelerate beyond that point but you can tell it's lacking power, same with 4th. If I free-rev in neutral, I can rev it but if I rev and hold it at 3500rpms or about that point it breaks up and doesn't want to hold steady.

*I've checked my coil packs for power, resistance and my plugs are new. I even took them back out, cleaned and regapped them.
*I checked the ignitor by measuring continuity between all the different posts. Its good
*MAF is good. I replaced it with a new one, and I have continuity between the signal wire to the computer, continuity between the ground wire and the computer, and I have battery voltage to the sensor
*New Coolant temperature sensor
*New/used CAS because my old one had a cracked housing.
*Timing is on the money

Interesting to note that when I was timing it seemed like the signal wanted to jump around a little. I'm kind of leaning towards the CAS being bad, because of the timing light jumping around and the way it's idling but thats why I've come to nico to see if anyone else has some advice to offer.

[Steady_One_S13]

You didn't mention fuel pump or fpr. Check those out. Not sure on how to test or check the cas. I'm leaning towards a bad fpr. my2cents.

[cypher02xd]

s***. Those are important details that I forgot! I'm running an ISIS external FPR with a walbro 255lph fuel pump. Fuel pressure is at 38psi at idle.

[Steady_One_S13]

Fuel pressure should be at 36 psi w/ vacuum. 38psi shouldn't hurt it.

Injectors??

[S-ICHISAN]

i run 41psi at idle...
wit no prob.....
look need to check for boost leaks.....
if all else is good for sure then boost leaks r the next test area....
bad bov....boost leaking at hot pipe...theres alot that could b wrong
testing everything is the best thing b4 u buy anything new....
a multimeter or a test light will help
all main connections should have 12v for sure

[cypher02xd]

Injectors are good. Getting good power and all 4 are at 11.2ohms, which is within spec.

i run 41psi at idle...
wit no prob.....
look need to check for boost leaks.....
if all else is good for sure then boost leaks r the next test area....
bad bov....boost leaking at hot pipe...theres alot that could b wrong
testing everything is the best thing b4 u buy anything new....
a multimeter or a test light will help
all main connections should have 12v for sure

I've checked for boost leaks using a boost leak tester and I'm fairly sure I have everything buttoned up. I'm going to recheck it again Tuesday (next day off) to make sure I know without any doubt that I don't have any leaks. I have a multimeter and test light. With the way its acting I'm inclined to think it's a sensor problem, computer problem, or maybe ignition related since it happens at the same rpm consistently.

[CRyan]

sounds as if you might be running super rich on start up - Thats the reason when you give it RPM, it cleans out.

But that is only an assumption for I haven't ran into this problem before.

[zachattack_5491]

Highly unlikely, but I had the same problems on my SR and the problem was my ECU.

[PyR0NiAk]

I know you said the MAF is good, but it still sounds like a MAF issue. This would lead to it being the ECU as zach suggested. Unplug your MAF and see if it behaves the same way. I bet it won't make a difference. If it doesn't try swapping ecus with someone.

[Street_Science]

Does the maf have a built in iat sensor like most hot wire and hot screen mafs?.....

[zachattack_5491]

Does the maf have a built in iat sensor like most hot wire and hot screen mafs?.....

Not technically. With the stock KA there is a IAT sensor, but it's not important and I've never even seen one in use. They are usually mounted in the stock plastic airbox, so when you get a cone filter... the sensor must be removed.

[cypher02xd]

Not a MAF issue. Unplugged it while idling and the car dies right out. Throw in all the other stuff that I checked and I'm certain its not a MAF problem.

Highly unlikely, but I had the same problems on my SR and the problem was my ECU.

I'm starting to lean towards maybe an ecu problem or possibly still ignition. I made a little bit of headway today. I started by double/triple/quadruple checking everything and the first thing I started with was my timing. I fired it up this morning, didn't really want to idle right until I gave it some gas than it would idle OK. Once it warms up its ok but will intermittenly run rough then clear out. Anywho, when I threw the timing light on I noticed my timing was off. I was certain I had set it right when I did the CAS so I went to adjust. I could only get about 7* advanced out of it!

So I figured I had installed it incorrectly. I pulled the valve cover back off to pull it and realign (i had wanted to remove the one guide anyway) and put it all back together folowing the FSM to the letter. Put it together and still only can get 7* out of it. wtf? So I took it for a drive and it is BETTER than it was before. It doesn't buck and kick nearly as much as it did before but it's still lacking power that much is obvious. I can now get to redline in 1st/2nd if I don't go WOT. So to sum up symptoms/today:

*Found timing was off, pulled cas, redid and still can only get 7* out of it
*Car doesn't want to idle right when first started
*Once warmed up it intermittenly will run rough then sort of clear out and idle smoothly
*It's running BETTER now than it was before but it still isn't happy

My thoughts are that something is telling the computer to pull back timing for whatever reason, thats why I can't get it to where it needs to be AND why it runs rough randomly. ECU has NO CODES, except for 55.

[CRyan]

Am I just misinformed, or are you WAY OFF with the advancement in your timing. I thought you retard it to 15 below TDC.

Have you checked your coolant temp sensor?

[cypher02xd]

CTS is new, though I suppose that doesn't mean it can't be bad... Timing should be 15* BTDC, I'm about a mark and a half off from that but I'm out of adjustment. Second to last mark from the right.I

[cypher02xd]

Could the IACV cause anything similair to this? I noticed that If I turn the adjustment screw it doesn't seem to make a damned bit of difference in the idle. I have a spare one here, and its easy to get to with the ISIS intake manifold... maybe I'll swap it just for fun.

[CRyan]

Could the IACV cause anything similair to this? I noticed that If I turn the adjustment screw it doesn't seem to make a damned bit of difference in the idle. I have a spare one here, and its easy to get to with the ISIS intake manifold... maybe I'll swap it just for fun.

Doesn't hurt to try, it'd be great if it was just that, eh! Keep us informed, that way we can come back to it!

[PyR0NiAk]

You don't unplug the MAF WHILE idling. You unplug it, THEN start it. I bet it'll behave the exact same way.

[cypher02xd]

I bet it doesn't, but I shall try it anyway. I don't even care how much it costs to fix it, I just want it to run right so I can enjoy the fruits of my labor.

[CRyan]

I bet it doesn't, but I shall try it anyway. I don't even care how much it costs to fix it, I just want it to run right so I can enjoy the fruits of my labor.

I know the feeling man. Exactly.

[PyR0NiAk]

The reason I'm saying maf related is because the ~3k rpm deal is limp mode. Most common reason for limp mode is the MAF. Also, the initially low idle is exactly what mine does right now. (My maf's unplugged)

[cypher02xd]

It absolutely won't stay running with the maf unplugged. I unplugged the knock sensor because some of the symptoms fit. It starts right up and idles now. It's still running rough BUT it doesnt act like its going to die out anymore when I first start it. Something must be telling it to pull back timing and dump fuel.

[PyR0NiAk]

The knock sensor tells it to do that when it senses knock. Sounds like you have a fuel issue. You said you checked the ohms. Did you actually pull the rail? Also, have you checked for codes?

[cypher02xd]

I pulled the rail and primed it a couple of times to get pressure into everything to check for leaks. Thinking about pulling the injectors out to check for physical damage and to put power to each one to make sure they 'click' properly for me. There were no leaks at the injectors and there are no codes. Going off of purely sound (using the ol' screwdriver method), the #4 injector didn't seem like it was clicking as quickly as the rest. I'm close to just getting another set of injectors, and the splitfire ignition system so that I can just cross them off my list.

[cypher02xd]

so I got it to run better. I took the cas out and turned it a tooth to get it to advance it more but now I can't retard the timing enough to get it to where it needs to be. If I put it in correctly, I can't advance it enough to get into spec. I don't get it.

[PyR0NiAk]

Maybe it was mentioned earlier, but have you actually set your cam timing? Pull the valve cover, set the crank pulley to the 2nd notch from left. (This sets the #1 piston at TDC.) Then set your cams at 10 and 12. (The hex keys not the notches) Then, you take and make sure there are 9 links BETWEEN the notches on the cam gears.

[cypher02xd]

I've had no reason to believe the timing to go off, but I know what I'll be doing Tuesday on my day off now.

[PyR0NiAk]

It's a 20-30 minute job if it's your first time. Once you've done it enough, you'll spend more time taking the valve cover off than you will actually setting the timing.

Just in case my directions were confusing or too abbreviated: http://www.frsport.com/How-To-Set-Crank ... _t_25.html

[cypher02xd]

The timing looks pretty good to me.. but heres some pictures since I don't want to put this damn valve cover back on AGAIN just to take it off. There are 9 links between the marks on the sprockets. I restabbed my CAS and put it back in the way the FSM says to do. Lets see what happens now...

[PyR0NiAk]

I'm looking at your pics but the exhaust cam gear is messing with me. I'm not seeing the key... It should be at the 12 o'clock position... I'm looking at it on my droid in a mildly dark room so maybe my eyes are just f*** with me...

[cypher02xd]

So the problem still persists. I now have the consult software and my ignition timing is spot on. Watching the software my timing will sit right at 15* btdc, but if you watch closely it'll jump to 17* everyonce and awhile, and when it does that it'll usually stumble for a splut second. it'll also drop to 12* every once and awhile. So, it has to be ignition related now or CAS.