I have an 89' Iroc-Z with the 350 Tuned port and automatic transmission. Starting late in december in would stumble occasionally but ran okay. I parked it for the month of January, then went out to start driving it agin this month and here is what i have.

*Rough idle
*grey smoke on start up
*in gear it lurches and stumbles, if you go wot it sound like timing is wacked
*Fuel pressure is 38 @ idle with vacuum 42-43 @ idle no vacuum
*runs really rich, fouled two plugs in about 2 hours run time

here is what i have done-
*checked fuel pressure, leaks off really slowly unless you pinch return line, were talking like a half hour to an hour to leak down to 20 psi.
*set timing with older style light, ^may be the problem^
*changed to new delco plugs gapped to .035"
*replaced cap and rotor about 3 months ago
*cleaned and had ignition module tested

Please someone help me out, im ready to pull my hair out!

 

grey smoke you say? Hrm... Im just wondering if in conjunction to a timing issue you have bad valve seats or perhaps a bent valve or something. (which would imply that oil leaks into the combustion chambers on startup) though that normally produces blueish smoke... coolant being burned produces white smoke... hrm.


So how does it run when not in gear?

 

when its in park or neutral its idles almost perfectly since cleaning the contacts and bottom of the ignition module. I doesnt burn any oil, or coolant. I'm going to try and find a better timing light to check it with, i have heard that the older style (goes between plug and wire instead of clamping on wire) can cause misreading on an hei system. I just remebered that mid january i was checking my ECM grounds as a possibility for these problems and adjusted my timing and it just went down hill since that.

 

ttt:lala: :lala:

 

Check to see if you switch to closed loop
check codes
Switch your CTS

 

I have checked for codes a couple of times already, I will hook the scanner on tomorrow and see if its going to closed loop. Didnt know a failing CTS could cause these, hopefully thats all it is!

 

i had an intermittent problem which sounded a little like that. took me forever to hunt it down but with scanner software i found it was an intermittent break in the cts wiring right up by the connector to the cts.

 

also check for vacuum leaks. damn those hard plastic vacuum lines!

 

I had this on my 88 GTA; confused me for ages. Turned out that the ECU wasn't reading the temp sensor right and was setting the mixture really rich.

This caused it to 'hunt' at idle, smoke on start up, foul-up the plugs and run at best 100 miles to a tank.

Matthew

 

About how much vacuum should i be pulling at idle, last time i checked it was around 17

 

Did you test the ignition coil? I just fixed a problem where my car would idle fine but when I drove it for a few minutes it would surge/misfire real bad and die .

 

What does CTS stand for...I'm drawing a blank.

 

cts = coolant temperature sensor

 

17" hg vacuum is decent. but that doesnt necesarily mean you dont have a leak. check everything very well. i found an insidious crack in a vacuum line running through the firewall. was screwing up my air fuel mixture because it was drawing unmetered air causing all kinds of problems with driveability.

 

okay, im going to get to work on it after school. If its not going into closed loop then it is the CTS right?

I will check out all of my vacuum lines really good, I wish I had the time to go through and replace them all, it wouldnt hurt.

 

okay, replaced the CTS, and it still runs like sh*t so im going to reset the computer and hope that will help it, or maybe set a code, that would be cool but anyway, keep the replies coming

 

ttt

 

Still runs like crap.
Don't know if the car is running as rich or if the rich condition has subsided any after the CTS change and computer reset. Don't know if there are any codes now, and finally don't know if your in open loop, closed loop or limp home mode.
Also you failed to mention if this happens only at start up or after warm up or vice versa or continually. But that one I can overlook as I didn't particularly ark for, nor was it volunteered previously.
Additionally you may want to add what your timing is set at, what your fuel pressure is, and if they did a complete test of the module, if you greased it upon re-installation, if you double checked the cap and rotor which you installed a few months ago when, as you purported in the first post, the trouble started. You have to remember we don't have the car here in front of us to fiddle with.

 

How true it is, here's some more info for ya

*Fuel pressure = 42 at idle no vacuum, 38 at idle with vacuum
*timing 8* BTDC
*Havn't reset computer since CTS change
*Will put scanner on tomorrow to find out closed/open loop status
*symptoms are always, start up after warm up, tried driving it around for 10-15 minutes, still there.
*autozone tested the module on their machine it had like 8 checks and then a final pass/fail he did it 7-8 times to make sure it got really hot!
*Cap and rotor are almost as clean as when they went on, rotor has a little black by the wire strip on top, cap has no discoloring or anything on it.
*Greased module and dizzy plate with white stuff they sold me the zone, came in a "wells" box
*put dielectric grease on connections to module
*No burned/melted plug wires
*grounds on back of drivers side head were loose, tightened, made no difference


Ive had my car run in limp home mode before (when installing self done PROM, running stock one right now, without Moates adapter) and this doesnt seem like limp home mode, but how can i tell for sure?

 

K, throw the timing back to 6º or maybe even 4º if we have to, throw on the old cap and rotor, (just to be sure) check your wire routing, you <i>would NOT</i> beleive how often people swap the #5 and #7, reset the computer, hook up the scanner. Also check carefully for burnt or cut wires.

BTW does it ever stall? Just for S&G unplug your MAF while running and report what happens as well. And you did clean both surfaces before greasing like a good boy didn't you? Also as an aside how much fuel is in your tank? You may have a compound problem.

 

dont have the old cap and rotor, threw them right away didnt even keep some of my old wires just in case

It was almost out of gas, so i went and put in like $6 of 89 octane to see if it was that, didnt help any. I'll try and get it filled up tomorrow if I can get it to the gas station.

I cleaned both surfaces with emery cloth before putting the module back in. The only times it will stall is if you flick the throttle real fast then it just dies.

 

just checked for trouble codes, and the computer flashed code 42, i think it may be from trying to set my timing, I unhooked the battery to clear it out. Hooked the battery back up, no codes on start-up. Unhooked ECS it made the idle drop down and the car ran real bad, plugged it back in and now i have a steady SES light.

 

Did you check the coil pickup inside the distributor. That will cause all kinds of problems similar to what you are experiencing. Plus, its cheap but a pain to change.

 

I'm sure you have checked this, just didnt see it in your list unless I over looked it. Its my current problem that I'll take care of on the weekend or so.

Checked for burnt plug wires right? Freaking headers got me twice on that. lol

>opps... just saw that you checked the plug wires.

ok well.. I have a simmular problem, when I have it in reverse and flick the gas sometimes, it will die. My problem I belive to be somewhere with the ESC (electronic spark control) module. Its been causing alot of stumbling when the check engine light pops on, but never untill that light pops on. Not sure on your car though. I'm keeping tabs on info at the electrical problems portion of this web site.

 

Matthew - sounds like I'm going through your problem - it hunts at idle, smokes on start up and only gets about 100 miles to a tank. Do you recall if it tripped any CEL? My is intermittent - flashes occasionally - never steady - but is not lit when I'm stopped/parked.

What did you do to fix your problem? I bought my car used and it seems like someone tweaked the wiring so the fans run all the time.... I know there are some concerns with running too cool and not warming up, but I only drive the car during the summer so I wasn't that worried about it.

 

Havnt checked it yet, i was under the impression that when the pickup coil goes out, it just dies and thats it. Or will it cause all kinds of crap to happen? Where is it, and whats the procedure to remove/replace it?

 

When my pickup coil went bad, it acted up for about a week. Engine stumbled when I accelerated fast , lots of backfiring, then death. The coil is locate inside the distributor, around the shaft. The distributor must be removed and disassembled. The good thing is the part is around $12 to $15.

 

sweet, i'll grab one and put it on tomorrow! Hopefully thats what it is. :lala: :lala: :lala: :lala: :lala: :lala:

 

Got it fixed!!!!!!!!! I put on a new pickup coil, while I was doing that, i noticed that the white mark on my timing indicator was at 4* after TDC so ive been driving it like that for over a year that explains alot of the problems. Set it to 6* BTDC and it runs excellent now, break the tires loose way easier and better. Doesnt seem tor un as rich, and the hunting Idle went away!!! :hail: :hail: the Pickup coil!!!