Need suggestions and comments.....
 

Hello all, its been a long time since I have posted. I have been trying to diagnose a problem with my car for the last few years with no luck. I will not go into the whole issue. As some already know and I have tried several sites to see if any one has had similar issues with no luck. So now it comes down to this........

I have decided I will have to do one of two things to be able to get this car on the road and be reliable. First a little background. The car is a 1988 IROC-Z with a 5.7 TPI. The car is all original with only 28,000 original miles and I am the first owner. Here is where the suggestions come in.....

1. Have the original motor completely rebuilt installing new parts, cleaning everything, new wiring and sensors as needed.

or

2. Replace the motor with a new crate motor with a carb and no electronic BS.

Have at it, all opinions and suggestions welcome. Sorry if this post in in the wrong area.

I guess that is kind of a shotgun approach. You've tried several sites. Have you tried any good auto techs?

I'd never can EFI, but that is just me.

What is the main issue you are having?

tried about all I can think of at this point. Talked to several techs and they dont know either. Been sinking to many dollars into it chasing different things and ideas. I probably could have bought a new motor by now.

Its not one issue. Its a combination of things happening at the same time.
I think I posted up here once about the problem. its a big write up. I'll try to find it.

Here is my original post....

I am hoping some one here can help or offer some advice on my engine issue. I have and 88 Iroc with a 5.7 TPI. It is the original motor with just over 28 thousand miles. There have been no mods done to the car. I am the original owner and know all work that has been done to the car. Here is the problem:
The car will start with no trouble. Once running however it will backfire and chug. Most of the time in order to keep the engine running I have to play with the throttle to keep it going, sometimes that doesn’t even work. During this time the check engine light will be on. There are no codes stored. On occasion the car will start and run correctly. I might even be able to get it on the road and drive for a few miles before it begins again. Once under load on the road the car might be able to hit 30 MPH, all the while backfiring and chugging and shifting hard. Playing with the throttle some times will keep it going but most times it will just stall out. This can happen even while idling in the driveway. Once the car is warmed up a steady blast of hot air is coming out of the passenger side of the car, heating up the floor boards and rocker panels on the passenger side. It is also sucking up gas like crazy.
Some background on what I have done so far. The car was in storage for 10 years. Once taken out and put back on the road I had all fluids changed (oil, antifreeze, trans, differential, brake), along with a tune up. New plugs and wires, new battery cables, new alternator, and new mass air flow sensor. That was 2 years ago. The car was running fine but was down on power a little. Last year it had a coolant leak from the intake manifold gasket. Leaking out not into the engine. Had all gaskets replaced and threw a new thermostat in at the same time. The distributor was also rebuilt because it was rusted. Also replaced the ECM because the check light would come on, again no codes were stored. The car ran fine for 250 miles before the above started happening. Was told maybe the cat was clogged. I have since gutted the cat. No change. Also replace the temp sensor. There are no leaks anywhere. The exhaust system is original and also not leaking or rusted. My next step is to try Sea foaming the engine to see if that will help at all then replace the fuel pressure regulator.

Have since replaced the fuel pressure regulator and an air sensor. Again it ran great for about 200 miles and now back to what is written above.

I have 2 ideas...
1. you replaced bad ecm with aftermarket reman. piece of s&*t
or
2. someone put sugar or soap in your gas tank

Hard to diagnose something w/out proper tests. ie: fuel pressure,ecm,coil voltage,etc...

this is the cars 3rd ECM and it is a remanufacted one.
Car is never left anywhere where some one could put something in the tank.
Its in the garage or was at a show.

huh. backfire and chug shouts timing & fuel, not engine issues.

*fuel pressure check would be nice. when it is failing.
*what does "distributor was also rebuilt" mean? Did that include both a new ignition coil and a pick up coil? Or is that just a module/cap/rotor?
*has anyone gone over the whole harness looking for problems like mice nibbling?

Or bad grounds or O2 sensors.

grounds are a good call to review. i was thinking about injector issues since he car sat so long. but i think that would be a more constant issue

Or maybe funky timing depending on temperature and how long it took to click off those 200 miles.

I've had a issues with distributor modules. Finally ended up getting an ACDelco module. I went through two Accell modules and both of them were junk. Sometimes the car wouldn't start, sometimes it would start but run rough and other times it would run perfect. It also stalled and left me stranded which is when I switched to the ACDelco part, haven't had any issues since.

dont get me going on accell junk. never ever ever again

Same. 126 miles out of brand new coil packs? GFY.

Id put a cheap china BW part from advanced auto on my car befor I used a Accel piece of s&*t

I am not sure how much of the distributor was redone. Probably just the module/cap/rotor.
Wiring harness was never checked. I have done a check myself of the wiring above and below for as much as I could see. Did not notice any bad wires. Mice did make a nest under the Plenum using the hood insulation back in the 90's but the wiring was untouched as far as I saw on my visual check.

Which grounds are you thinking? Shouldn't there be a stored code if the sensor was bad. can't get any code flashes. Of course I am using the jumper method seen as how I don't have an OBD1 reader.

I'd start by checking all of the underhood grounds first.

Timing was reset by me. After getting it back from the coolant leak the timng was set to high. It took about 7 days to go those 200 miles. Roughly close to 20 to 25 miles per day give or take.

I do want to drain the fuel. I just have to get something to do it with. The fuel has been in the car a long time (about 2 years) but I use stabalizer on it every year during the winter months.

Oh man.

Sta-bil gets you another 3 months, MAX. The advertise 12 but in independent testing it was proven to be more like 3.

Personally I would not spend any more time on anything else. Get fresh gas right away. Premium.

If that is true about sta-bil that would explain a lot. That will be the next step then. drain the gas and fill with fresh. Always use premium in the car. It won't run on anything but. If that doesn't help I will look at all the other options people have suggested.

Thanks for all the input everyone!
I let you know the outcome.....

Yeah, probably an outside shot, but dealing with old gas can drive you crazy.

probably a few bad parts such as icm, o2,fuel filter,cat, ecm,fuel pump, i had the same problem on the 88 gta it ran fine and then started to back fire and sputter all it was the fuel filter was clogged , i had the same problm on my 94 blazer all it was was when the previous owener changed the fuel pump he used the alligator clips instead of the hose clamps

:facepalm: