My car blew a heater hose and overheated the other day, and now it's hard to start and keep running while parked/stopped. It'll start, and go to 500 RPM, then will die, unless I feed it gas. Then I have to drop it into drive/reverse to go anywhere. This is not an optimal mode of driving.

But it doesn't do this all of the time. At night, when it's colder outside, it runs fine; Perfect even. Even after the engine makes it up to temp. So I'm mostly convinced this is a sensor/wiring issue, and not an engine problem. Most engine problems aren't intermittent.

I took a datalog of the car, and it shows my BLMs are up, and my INT is down just before the engine dies when I pull up to the stoplight. My Bypass check enable is also enabled in the flags section of TunerPro.

I haven't found all that great of a datastream definition file either, some of the stuff is just plain wrong. Any help is appreciated.

On a side note: I think it might be that spark control module on the dizzy.

Bump? Anyone have any ideas?

What got wet when the heater hose blew?

Everything on the front of the engine. The hose broke at the nipple coming from the front of the lower TPI intake. Everything up there seems to work fine. Fans, alt, power steering, etc.

I've had a similar time with the spark control module, overheating and failing, and it's been in there for two years now, almost to the day. It doesn't throw any computer codes, so maybe that's actually it? Might just get a new CC dizzy, 'cause if I remember, mine didn't look too good.

If you have any other ideas though, do share them.

Bought a new Holley dizzy. Installed. Did my timing. Ran great. Until I went to start it again after the test drive. Starts, goes to 750 RPM, then drops off until it dies.

Installed a new coil. No effect.
Installed a new IAC valve. Worked great for three days (I think it was just the fact that since it's intermittent, it didn't act up.) now problem is back.
I'm at wits end here. I cleaned my TB, replaced all the gaskets in it, re-set my TPS and IAC, and even set my idle air.

Doesn't anyone have ANY ideas on what could go bad from overheating an engine that would only affect it's ability to idle?

No codes. Nothing too funny on the scanner (my O2 sensor is bad, covered in carbon from my bad valve seals. >.<) but other than that, everything looks fine. :/

Come on. No one has anything to say? Just throw something out there. Sensor, engine hard parts. Please! This is driving me nuts, I shouldn't have to pop my car into neutral at stop lights or around corners so it doesn't die!

How hot did it get? Any water/foam in the oil? Did it also do this before the dizzy? It's just a hunch, but I'd be looking for another MAF to try. You might also try running it in open loop with the EST disconnected and see if it still does it.

I'd disconnect every connector in the engine compartment, especially those that could have gotten wet, spray them with a cleaner (both sides), blow/dry them out, and give it another try.

If the temp gauge is a smooth scale, I'd say 280. I was in traffic and couldn't pull over until it had gotten too hot.

Haven't drained the oil, was gonna do it today matter of fact, just to make sure I don't have a blown head gasket or a leak in my oil cooler.

Did it before the dizzy swap, so I know that was completely ineffective. But now I don't really need to worry about any dizzy problems, so it could be worse.

The EST is the one on the driver firewall, and the ESC is the one in the dizzy, right? I'll try disconnecting it next time it's doing it.

five7kid, I'll look into it, but I'd think if it were something gumming up a connector that it'd be more constant and less intermittent.

I've also noticed that it happens most often when the car has been ran for a short amount of time, turned off, and started again.

The MAF just a little more than a year old, and is the thin-film Micro-Tech type, and not the hot-wire type.

I don't know what the TPS should read, but you can check the resitance and make sure that it is a smooth transition from Idle to WOT.

S'posed to read .54 volts, and it does. Smooth transition from no throttle all the way to WOT which is over 4 volts, as specs.

Sounds kinda like what my issue started with. Check the resistance of each fuel injector. If you have one that is starting to short out it can cause all kinds of crazy issues. I think yours should read between 11 and 14 ohms. Look it up in a book to be sure though.

Also it could be an intermittently sticking EGR. If the EGR is open even slightly at idle it will die. I would personally start here. I can't remember if you will have an electronic or vacuum EGR. If it is electronic take it apart and look at where the spring loaded plungers are. Maybe there is a piece of carbon or oil (You did mention valve seals before) that is causing your headache. If you have a vacuum EGR then follow the line from the EGR. It will connect to a solenoid that controls when it gets vacuum. Maybe it is going bad.

Just a few thoughts.....Hope it helps. Now if anyone would reply to my post......

Ohm'd all of my injectors, and they came out to 16.3 or so. All of them. So it's not them (wish it was).

Still could be the EGR, which sucks, as just to inspect the thing requires at least $30 in gaskets, and if I do that I might as well replace all of the sensors and clean up all of the crap under there.

Anyone know of a TPI bolt kit? I'm going for a machined/satin aluminum look with black oxide fasteners.

Edit:

So I finally got my PROM tuning stuff in the mail, and I flashed an ARAP chip for an 89 Vette (changed the fan switch and the other flag or two needed to run it in an 87-88 TPI), and popped it in the car. It runs great. Like, fantabulous. My BLM's and INT fluctuate quite a bit while driving, and with the new chip, my O2 sensor gives me really high and then really low readings. The MAF also says it's pushing 7.5 grams of air just sitting there with the engine off. >.< Gonna pull out the new chip and put the memcal back though, as I figure now is not the time to be doing mods.

I wish your car was here so I could take a look at it. Trying to diag a car over the internet sucks. Did any vacuum lines getting fudged? as far as a bolt kit go to true value. You can get some really good looking allen head bolts on the DIRT cheap. I have done this twice to other friends cars. Black ones are like 50 cents and the stainless are like a buck a piece. I'd really like to help you on this one.

It seems to be driving fine as long as I'm not in traffic, I'll be coming up there for my birthday (27th of this month. Woo woo!) so I could swing by then if I haven't nailed it yet.

It is driving me nuts though. I noticed that with the ARAP chip (still haven't pulled it) that I have different idle problems. When it starts, it shoots up to 1500, drops to 750, and then will hit 1000 until the O2 sensor warms up, but after that, it'll jump between 1500 and 750. :/

And according to TunerPro, the car is running WAAAAY lean at idle with the ARAP chip. Gonna go pull the computer now, because I don't need to troubleshoot two things at once.

Bam. Credit goes to jv9999 for calling it ahead of anything else.

I never noticed that my MAF had a reading before the car was started, and it didn't throw a code. Well, it didn't throw a code until I took it to a shop, where they proceeded to charge me $100 to tell me that it could be my MAF, and that they wanted $150 to fix the MAF wires (see PS) before they'd replace the sensor OR troubleshoot any further. I was 99% sure the wires were fine, and I paid them $100, took my car home, and did my own soldering on the MAF wires and it still throws a code and still has a reading of 5 grams/second with the engine off.

Which means the damn thing is bad.

PS:
I unplugged the MAF once to see if it was a problem a year or so ago, and the plug fell from where I stuck it when I was running the engine, and the wires fell on the belt, and chewed them up. I bought a new MAF plug with leads, but because I couldn't get my soldering iron to the car (was in an apartment) I just butt connected them with the really nice heatshrink butt connectors, and to be double extra sure, I filled the connectors with silicone grease so that there would be no trapped air to cause any kind of corrosion.

So, my MAF was bad, but that wasn't the cause of my problems. Something is still going haywire. Starts and then dies, unless you give it just a little bit of gas. Car will not start and idle, but if you give it gas for a while, it'll idle at like, 500 RPM, and be in serious danger of dying.

This was caused by an overheat, that was caused by a burst heater hose on the nipple coming out of the front of the block.

I'd like to see how this turns out, cause I was having the same exact trouble with my car. Except mine is a SD setup instead of a MAF.....

I adjusted my idle speed up a bit higher, (to around 750) and the problem went away....I thought this was due to my new camshaft though.

Either way, I have a new problem of the car sputtering under load (as if its not getting enough fuel) and sometimes even dying out of nowhere, and unable to start it until it sits for a while. I thought it was a bad TPS, but now I think its a clogged vent tube. the car doesn't stall when the tank is full, but still sometimes sputters under load, especially when cold.