OK getting somewhere - need more help

[ffvetteman]

Alright, still working on my ZR-1.

For starters, I put a new ECM in that Dandy97 let me borrow(thank you very much for letting me borrow the ECM Dan!!) and all the issues from before with the lights on the dash are now out and all appears to be functioning properly. However, it is still not running right, as it feels like it has a miss. With the new ECM in, I took it out for a spin and it ran and the power key would stay on, but again it did not have the power it should and feels like it has a slight miss.

I replaced the spark plugs with new AC plugs and that helped a little but still not there. The plugs were gaped at .45 and the car says it should be at 35. The plugs did seem a little worn out.

I took it out again and when I was driving it, I believe a little hard, the check engine light came on. I ran the code and it gave me 12 and 55.

Checking the shop manual, it shows code 55 as FUEL LEAN MONITOR. It shows that it either needs the lines cleaned, fuel filter replaced or could be a bad pump.

Problem is I dont have a fuel pressure gague to test the fuel pressure.

My question is where should I go next? What do you guys think should be my next step.

Again, I cannot say thanks to Dandy97 enough for letting me borrow the ECM and verify that my ECM was bad. The assistance given by Dandy97 and everyone on this board is incredible, and so helpful I cannot express.

P.S. the car is a stock 92 ZR-1 except for a Samco Air Duct. I was running a DRM chip, but am back to the stock chip until I get this solved.

[ffvetteman]

Should I start with a new fuel filter and go from there?

[tccrab]

Originally Posted by ffvetteman

Should I start with a new fuel filter and go from there?

Always try the simple/cheap fixes first, so for sure pop in a new fuel filter.

While the engine is hot, leave her running and one by one pull each spark plug wire. If all cylinders are firing then each time you remove a spark plug wire the engine will stumble, miss and make a different sound.
If you pull a spark plug wire and the engine sounds exactly the same as before, now you know where to dig deeper.
If your coils are operating correctly, you will hear the same crackling sound from each spark plug as you pull the spark plug wire. If one cylinder doesn't make quite as much crackling sound, you now know where to dig deeper.
Pop the hood open in a dark garage at nighttime while it's running and hot. If a spark plug wire is shorting, it will be quite visable. Look for a pretty blue or red glow.

Start looking for vacuum leaks, while the engine is running, spray a little carb cleaner at each one of the connections. It'll be obvious if you have a leak.
On my '90, the @!#$%^ing PCV connector behind the plenum leaks, as well as the connector just underneath the throttle plates. I've got the plenum off to replace bad fuel injectors, and will be replacing them when it goes back together.

Good luck!

TomC
'90ZR1 #792

[evl_twn]

I wanted to make sure both my pumps were working, and bought a fuel pressure gauge setup at Advance auto parts. It's about $40, but that's another tool I have in the box in case I ever need it again, or for another vehicle.

[ffvetteman]

OKI forgot I had a fuel pressure guage. So I hooked it up and Disconnected the fuse for fp1 and checked the pressure and then did the same for fp2 and each time had about 48 psi when just turning the key on. So it appears both pumps are working properly.

So get this, we noticed my coolant overflow was empty and the oil was about 2 quarts down. We topped them off and now the car is running fine. I feel stupid for not checking them first, but I didnt think of the oil because I have only put about 1k miles on since the last oil change.

We took it out for a run and the car felt perfect. It would up fine and drove great.

Did I just fix it?

[tccrab]

Originally Posted by ffvetteman

OKI forgot I had a fuel pressure guage. So I hooked it up and Disconnected the fuse for fp1 and checked the pressure and then did the same for fp2 and each time had about 48 psi when just turning the key on. So it appears both pumps are working properly.

So get this, we noticed my coolant overflow was empty and the oil was about 2 quarts down. We topped them off and now the car is running fine. I feel stupid for not checking them first, but I didnt think of the oil because I have only put about 1k miles on since the last oil change.

We took it out for a run and the car felt perfect. It would up fine and drove great.

Did I just fix it?

Level of coolant or oil will never make a difference on how an engine runs unless there is none in it at all. It'll start, but it won't run for long.

However, having said that, running your LT5 two quarts low on oil is a BAD thing and you should be thouroughly ashamed of yourself.
Have you checked the availability and price of a replacement engine lately?
Did you know that the main bearings (the ones on the crankshaft, the ones that will go first becasue there's not enough oil in the engine) are made of unobtanium right now?

The automotive gods have smiled on you this day, be grateful.

TomC
'90ZR1 #792

[ffvetteman]

Im on my way out back for a flogging.

[tccrab]

Originally Posted by ffvetteman

Im on my way out back for a flogging.

The flogging has been postponed.
Take the ZR1 for a drive instead.


TomC
'90ZR1 #792

[ffvetteman]

We did have it out yesterday after topping everything off and it was good. Now I put the old ECM in just for fun to dee what happens. Im gonna try driving it again.

[ffvetteman]

Ok now I took it out again with my stock ECM in it, it ran fine but after driving it for a bit, the service engine, service asr lights came on and I lost the speedo and the security light would flash. It ran perfect with gobs of power, even though I did not open it up. THe power key would not turn on. Could not get a code, so I think with a new ECm I should be done.