FocusVince

As the title implies...my lt1 overheated a few weeks ago. One of the bleeder screws somehow opened up and I lost coolant. I fixed the problem after work and its been running okay ever since, however there is a loss of power. It made my exhaust leak worse, which I know can cause performance issues, but the main problem is a high rpm miss. My question, is it possible that the engine overheating could have damaged my ICM or ignition coil? Could coolant have gotten on the optispark and caused that to **** out on me (I can't see any coolant down there but I suppose its possible)?

Thanks for the help, hope this isn't a costly repair.

FocusVince

anyone have any suggestions?

I also went to autozone to get a fuel pressure gauge so I could check that but they don't have one for fuel injected motors (the gauges only went to 15 psi..)

IronOutlaw

iTrader: (4)

I bought my fuel pressure gauge from Oreillys. How hot did it get? I warped the heads on one motor and it lost a lot of power, but it was ran very hot multiple times. Id fix the exhaust leak first thing. Check fuel pressure and check for any burnt plug wires then go from there.

FocusVince

I almost pegged the gauge...

Its ran fine ever since except for the loss of power and the misfire. I'll check the wires but I have a feeling it could be the coil since I've heard the heat can affect them. As for the leak, I plan to get long tubes if I can find them cheap, I've been messing with the stock manifolds forever trying to fix this leak and its become pretty much useless.

IronOutlaw

iTrader: (4)

If you didnt peg the gauge completely and shut it down in time I wouldnt worry about it too much. From my experience these motors are pretty damn tough when it comes to running hot. I have had experience with a bad coil once but the car just quit running completely.

FocusVince

I actually did notice that the misfire doesn't happen when the car is cold. Would that mean its a fuel pressure issue?

IronOutlaw

iTrader: (4)

If I had to guess, I would say that you are getting a bad reading at your o2 sensor because of your exhaust leak. The car is in open loop when it is first cranked and doesnt go into closed loop (using the oxygen sensors) until the engine is warmed up. Try unplugging your mass air flow sensor and drive the car. This will force it to stay in open loop not using the oxygen sensors. If it runs better with it unplugged then more than likely it is indeed the exhaust leak.

It is possible that your ICM is getting hot and causing a missfire but I doubt it. You could do the ICM spacer mod which is usually a good idea anyways.

FocusVince

my car is a 93, it doesn't have the MAF...

IronOutlaw

iTrader: (4)

Ok, I didnt notice that. You can just unplug one of the O2s.

FocusVince

yeah I'll look into that, thanks for the help!

gregrob

iTrader: (8)

You could have over heated the ICM. I would also do a compression test. ..

FocusVince

I was affraid of it being the ICM, its $160 at ghettozone

Mississippi

I'm having similar problems after my car ran hot. I've decided its the opti. I don't think running hot once could do that much damage to a coil. Or the icm. But I'm no expert. Try looking for an icm online. I imagine it will be cheaper.

FocusVince

After some more research I think my engine may be fine, the problem might actually be my fuel pump...it hesitates, stumbles at low rpm's, misfires at higher rpm's, and has almost no power in the higher rpm's...

I got to get a fuel pressure gauge

TwicePipes

When your bleed valve opened it pissed coolant all over the opti.

Sounds like an ignition problem IMhO.

Pull the opti spark harness out and make sure there isn't any crap or moisture in there.
Next reconnect the harness and make sure the connection is tight.

If you suspect a fuel issue, pull a spark plug out and see what it looks like.

Iv'e had several LT1 fbodys, a 93 also. Every ICM that went bad on mine would shut the car off with out warning.

FocusVince

I don't see any excess moisture on the front of the motor, so I don't think the opti is bad. My fuel pump seems to change pitches when it primes the motor, so I'm going to get a fuel pressure gauge and check that out.

However my alternator died on me today, so I guess that is the first step lol

djjab57

iTrader: (17)

I dont remember it being that much but if you get it there it does have a lifetime warranty

djjab57

iTrader: (17)

$84.99 is what the web site says

FocusVince

Well I have to get a new alternator first because mine **** on me today...

TwicePipes

The alt very well could have been your problem.

Also, if you replace the opti, dont get a cheap one. Get a genuine ACdelco or Delpi unit.

ThePartsLady on ebay has the best price and always has them on hand.