I've only owned my IROC for three months. About two months ago it would occasionally stall/run with very low RPMs. It stopped doing it so I chalked it up to something screwy in an injector, etc...

Well, it did it again yesterday. I was sitting for an extended time at idle (in line at a car wash that was having technical difficulties). I remember watching the temperature gauge slowly run up, then I could hear the cooling fans kick on and bring the temperature back down. I also remember being pleased that everything appeared to be working OK.

When the attendent drove it out of the car wash, it kept stalling. It had a very low idle and I had to nurse it home (it stalled out twice because I was too slow to left foot brake, while feeding gas with my right foot).

When I got home, I looked around under the hood for something obvious... Nothing obvious. SO, I went inside to change clothes (it was about 30 deg. F) and left the hood up. When I came out 15 minutes later, the car fired and ran fine.

I am starting to wonder if this behavior isn't temperature-related. Has anyone seen this?

 

sounds almost like the fuel pump is starting to have thoughts about early retirement.. sometimes they can be working great, then all of a sudden they give you problems.. then are working fine a little bit later..

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My `91 Z28 Convertible

 

What kind of engine does it have? What year?

If it's a carb car, I'd suspect the fuel in the lines getting too hot where the line goes right next to the exhaust, causing it to boil when it reaches the carb, which makes it spew all out of the vents and flood the motor.

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"So many Mustangs, so little time..."
ICON Motorsports

 

This is a L98 engine (5.7 TPI).

I hope it's not the fuel pump. I've been told that they are not pleasant to change on these cars.

Would these symptoms potentially be the O2 sensor?

 

I would suspect an injector, or maybe ignition module. The fuel pump is also a suspect. How much fuel was in the tank? You will typically notice a temperture related fuel pump problem when the tank is low. I would tend to lean toward something on the engine itself, such as injector. When sitting and idling, the heat will soak into the engine, causing the problem.

Next question is about the temperature inside the car. It is also possible that the ECM got warm and caused the problem.

Also, what year is the car? From past experience in other vehicles, the ECM for the speed density cars (1227730) it does have some of the heat related problems. Actually now that I look it up, I remember the ECM for the MAF cars (1227165) giving me heat problems once before, too.

Good luck! I hope I gave you a couple ideas to check out! Don't just start replacing the things I've mentioned though, do some thorough testing first!

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Working on:
'84 Z28 LG4 305 with 200,000 original miles!
Added dual elec fans.
145 MPH IROC Speedo
Building 430 HP 350
using primarily GMPP parts.
Block is STILL in shop! (Waiting for my to buy the rods!)

ASE Certified Master Tech

Starting to look like the Kicker poster child!

 

Keith,

Have you removed the distributor cap lately to change the water in there?

Cool temperatures can cause a lot of condensation in supposedly "sealed" enclosures, the distributor being one of them.

Car warms up, everything is good. Car cools down, suddenly you have missing and no power. Just a thought.

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Later,
Vader
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"I'm gonna talk about some freaky sheet now..."
Adobe Acrobat Reader 4.0
KaleCo Auto Parts

 

Just to respond to some of the questions above:

1) The fuel tank was full. I had just filled it up prior to going to the gas station.

2) The car did get warm inside. Instead of reducing the temperature in the car, I opened the window (hmmm, interesting).

3) This car is an '88. I'm pretty sure that this means that the car is a speed density car. It was mentioned above that heat problems are not unheard of on the ECMs on these cars.

4) Actually, I haven't "changed the water" (good one) under the distributor cap recently. I'll have a look.

Thanks guys. I'm first going to focus on doing the "right" things to get this behavior to happen, then begin checking some of the above items.

I'll report back any results.

As I said, I've seen this before: https://www.thirdgen.org/messgboard/...ML/003597.html