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Discussion Starter · #1 · (Edited)
OK folks, I think I've already covered most of the basics on this one:
Car:93gt, pretty much bone stock.
Symptoms: The car started idling a little rough two days ago, got worse yesterday. Also noticed that when you come off the gas, the idle doesent drop all the way back down to normal, it holds around 1k-1200 for a second or two, then drops again.
With the car just sitting, the idle will slowly drop, then stumble and occasionally stall (but not always,some times it'll seem to just teeter on the brink)
You can also smell gas in the exaust
Also, I started it this morning, when it was a bit chilly outside, and the stumble/stalling was more pronounced until the car warmed up

First thought was that it fouled a plug, (burns oil on 2 cyls) I check the usual cylinders, and indeed, one was looking pretty crappy, and the other was borderline. Replace them, cars's still doing it.
So far I've: Checked all the other plugs, all ok, replaced cap,rotor, wires,and coil (I just did the coil on general principal, since as far as I know its original)
Run throttle body cleaner through
Checked timing (with the spout in it fluctuates with the idle, with it out its at a solid 10deg. Also noticed that if I give it gas with the spout out, it seems to be running really rich, I can hear popping and occasional backfiring in the exaust)
Checked Vacuum, steady 13-14 lbs,
Ran car with IAC unhooked, no noticible change,
Ran car with MAF unhooked, car died after a few seconds
(The MAF was also cleaned about 3 weeks ago, but I havent pulled it out again)
I cant check the TPS, since i just found out that my multi meter is apparently dead:madas:
KOER I get 12,94,34. (I just got my reader a few weeks ago, and its had the 34 I just havent had a chance to screw w/ the egr yet)

Any ideas? Bad injector?
Thanks
J

Also, maybe unrelated, but maybe not, I also noticed a new noise coming from the engine, sounds like pass side, cant be any more specific, it sounds linda like a "tsk tsk" but seems to come and go(?)....
 

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Discussion Starter · #2 ·
Addendum:
I also just pulled the IAC off, disconnected the sensor end, and hosed the "valve" end out. It wasn't too nasty, but did have a little carbon. No effect on the problem.
 

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Discussion Starter · #3 ·
Also pulled the EGR, the bottom chamber was almost clogged with carbon buildup, cleaned that, the TB didn't have too bad a coating in it.
Got a new multi meter, TPS was at .93, now at .967.

Anybody? Bueller?

Jorge
 

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If you removed the IAC valve and nothing noticable... like stalling.. happened, it sounds dead to me.
 

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Discussion Starter · #8 ·
Does anyone know of a way to test the iac motor to make sure before I plop down the $ for a new one?
BTW, GhostDog, check your PM's :)

Thanks
J
 

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An exhaust leak can wreak havoc with EEC, especially if it occurs before the O2 sensor. It sounds like your secondary air (what the smog pump pumps) is inoperative on the left (driver's?) side. Check all of the smog pump plumbing, especially the hose next to the pass. side header. Check all of your vacuum lines too, because if it's fairly stock, it should be pulling 15 pounds of vacuum.
 

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Discussion Starter · #10 ·
meangreen92 said:
An exhaust leak can wreak havoc with EEC, especially if it occurs before the O2 sensor. It sounds like your secondary air (what the smog pump pumps) is inoperative on the left (driver's?) side. Check all of the smog pump plumbing, especially the hose next to the pass. side header. Check all of your vacuum lines too, because if it's fairly stock, it should be pulling 15 pounds of vacuum.
Hmmm...thats something to consider. I have had problems with the air pump before, I replaced it before we moved, (the pulley was frozen, but I wasnt shocked, considering it had sat for 2 years) the new pulley only lasted about a year before this happened:


I've checked the vac lines, actually went through and found 2-3 bad ones a couple of weeks ago, but I'll re check em.
Thanks again guys

J

BTW, wouldn't a leak/problem like that show up as a code, for instance a prob with the o2 sensor?
 

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You can unplug the IAC while the motor is idling, and if the idle doesn't change (the motor should about stall if IAC is working) then the IAC is probably bad. Now that I think about it, your exhaust is probably OK. I just know that the headers on mine rusted out and developed leaks around the welds for the flange that hooks up to the H-pipe, and the car was running way rich - but I was getting lean codes. And you're not, so I'm thinking this is all in your emission system.
The pump sends the air,first, to a valve which EITHER dumps the pumped air out into the engine bay, OR, sends the air to the next valve. This next valve EITHER routes the air to that tubing which connects to the backs of your heads, OR, down to the converters. There are also check valves
where the hoses connect to prevent exhaust from entering the air passages. Only, can air enter the exhaust. These two valves I described, are controlled by vacuum, which is regulated (on or off) by the two smaller solenoids mounted on the rear of your pass. side strut-tower. The larger one does the EGR. EEC tells these solenoids to open or close. It sounds like they're electronicly OK, but inspect them for cracking (mine looked like water had froze in 'em). The EGR system works the same way. My EGR solenoid was clogged, but I just hooked a battery (9-12 volts) up to it and blew through it - easy cure.
Check all of the associated vacuum lines carefully, they're probably brittle. I just replaced mine with rubber hose and vacuum tees. Also there is a vacuum reservoir inside your fender well - make sure this is connected (or the line is plugged). There is a check valve which goes to the reservoir, it is up by the solenoids. I don't think it can create any noticable problems, but mine was bad.
I suspect that your problem is a leaking or kinked hose in the pumped-air circuit, because the right side of the engine (where the pumped air goes first) is OK. Check that big hose which run along your pass. side strut tower. Equal length headers will burn a hole in that hose. But also check every hose and tube in the circuit - from the pump to the heads and converters - that's where I suspect the problem lies. The only other thing that could cause (or indicate) a smog-pumped-air problem on one side, would be a bad O2 sensor or maybe an exhaust leak. But judging from the noise you described, I'd say that something is leaking. That could also be an exhaust port-to-header leak. When the car is idling, use a vacuum hose held to your ear to pinpoint the leak sound.
A plugged converter might be the ultimate culprit.
 

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Discussion Starter · #12 ·
Thanks for the info man, I'll check it out...If I can keep it running long enough.
Going to work tonight, the car started dying for no apparent reason every 2-3 seconds, even if I was on the gas. It was like the ignition was turned off. It took me 7-8 tried just to get through the intersection where it started, and coast into a parking lot....
I tried cranking it again, and it was running fine (or as well as it had been) and I was able to drive home...WTF...
I just found out how to check the IAC, and the solenoid seems ok, so the troubleshooting shall continue:(
 
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