Drivabilty issue.

[BBBAD94ZR1]

I hope you guys can help me out. I got my Z home today a 94 zr1 10k miles. The owner washed off the engine with a hose a big no .
I blew it off and the air cleaner had some water in it. No much. Here is the issue. I drove car for around a half hour mellow, I got on it a few times not going past 4500 rpm and I noticed a stumble. Drove it a bit more and I noticed if I shifted form 3rd to 4th at low rpms the car hesitated kind of like it was missing or starving for fuel got on it and it did not happen for a while. I let the car sit for a few hours took it back out and it ran better however when driving in 5th around 50 to sixty under accel the car stumbled. Go to 6th and it really ran bad drive it hard and its ok when in to high gears under light accel it stumbles sometimes? .
The car also had the chip changed here is the number of the one not in the car GM#16209008, the one in the car is 12528772 gr.3.670. Anyone know what the difference is between these two?
Please give me your input. Anyone know of a gm dealer in Nj who has a Zr1 tech? I hope its something easy to remedy.

Thank you
Ray

[black92]

sounds like an o2sensor. my 92 done the same thing. you might put it on a computer to check. hope that helps

[WB9MCW]

i would say first thing to do is to figure if it is electrical (spark/ignition...which might be from the hose job) or mechanical ( suspect would be bad fuel pump psi or injectors...low miles can hurt both by sitting around too much!!!) funny no dic light to help with trouble codes clues...sorry to see prob's right off the bat with ur new baby but not to worry ull get her up to snuff!!! u need to get tight with tomtom he just went through the new to u low miles zr-1 blues...TT will be a great asset to u for ideas because he has just been there!!! I sent him a pm so he will p/u on the post!!! Plus TT lives in NY!!!

[tomtom72]

Hi Ray,

Listen, does she give any "SES" light? Did you check for codes? When the stumble happens do you get a "SES" light, even briefly? Did you scan it?

Okay the sum total of my megar understanding of EEC is the ECM has two types of things it does:
1.) Operations it controls.
2.) Sensors it monitors for info to make control decisions.
If the trouble is a malfunctioning part that is not in either of those departments than you would not likely get a "SES" light & a DTC stored in memory, unless the part is related to something in either #1 &/or #2.

Your problem could be that water got to the injector connections, I can't remember if they had water-tight connectors. Or there could be a water induced problem and another part failure happening at the same time. If water got down the plug holes that could be the source? If water got to the coils then that could do it but it's hard to say where the water got to. From your description it seems as if this is random...like the water is doing the deed. I have a scan tool BUT I don't have any software for a OBDII set up. I whish I could give you a better input...if you need extra hands shout at me & I'll show up! Just a shot in the dark...how is the fuel filter? On my car the one from BG was still in it after 15 Yrs!!!! along w/plugs & a/f & pcv's!!


Tom
Oh, I'm just a rookie too, so I can't say for sure that I can do any thing but try to assist you....if I had the answer I'd fork it over...but I'm willing to help ya if ya want another body. I'm sure one of the senior guys will be along to show you the light...I know that for a fact!!

[BBBAD94ZR1]

Thats for the input guys, Tom no codes, no engine light, strange.....
I called Halibek and he said change the plugs, what do you think?
Looked at the plug holes dry. I suspect water also, the owner hosed of the engine put it in the trailer and it sat for two days in -10 degrees . I also fell sitting for 8 months and just getting started to operation temp does not help either.
The fuel was half a tank and I filled it up.
Im gonna change the plugs and go from there.
If the problem persists Ill give ya a call.
Thanks
RAY

[tomtom72]

Hey Ray, I defer to Mr Haibeck!!!!!

Yea look man I offer any help I can give ya, which ain't much 'cause I don't know much...but PM me if you want another rookie to lend a hand in person! It seems to me that plugs are cheap & why not give'em a shot. I wish I knew what Mr. Haibeck forgot about LT5's

PM me if you need to....don't hesitate.

[BBBAD94ZR1]

Well today, I changed the plugs and oil. Took it out and the same conditions. I also noticed at idle the throw out bearing makes some noise.
When you push in the clutch it goes away. Can you grease it and has anyone ever seen this before on a low mile car. I guess sitting it the worst thing for these car.

Any ideas?
RAY

[tomtom72]

Hey Ray, Sorry I didn't know about where you lived or I would have for sure given you a shout & stopped by on my way home! It would have been cool and I would have brought my tools!

Now on to the business:

Did you change the fuel filter and then do a fuel pressure test following the Helms manual? If not, swap out the filter...autoZone has them...and do a pressure test. I can't say for sure that is the root cause but the FF is easy to change. Oh, you do have the Helms manual, right?? If you have access to a scan tool it would be good to do a reading with the motor running in "open loop" and "closed loop"...I kind of learned how to interpret that data when I needed new injectors.

Stupid Q...does the car miss as soon as you start it or does it take a few minutes before the miss becomes evident and does it get worse the longer it runs???

The "noise" from the trans/clutch thing...when you step on the clutch you hear the noise? If yes and you pop it to the neutral gate and let off the clutch you still hear the noise?? Usually the T/O bearing makes noise only when the clutch is depressed and usually the noise quiets &/or leaves when you are off of the clutch, either in gear & moving or in neutral.

Don't feel bad about this...I have a theory about low mile virgins, like yours & mine...the worst thing is for these cars to sit and then be used...it causes more problems than if you just use them every chance ya get...screw the milage! My car came to me w/8,000 miles on it and I had clutch hyd. system problems after I drove the son of a biach to BG & back. I swear the car thinks I'm a slave driver!

Look man here's my digits...914-663-1201...use'em if ya need to...feel free...you are not alone in this and we are a tight group, we don't leave any one behind!


Tom

I think the noise you are hearing from the tranny/clutch with the pedel up is the dual mass fly wheel...especially with a miss, it sounds real swell!

[tccrab]

Originally Posted by BBBAD94ZR1

Well today, I changed the plugs and oil. Took it out and the same conditions. I also noticed at idle the throw out bearing makes some noise.
When you push in the clutch it goes away. Can you grease it and has anyone ever seen this before on a low mile car. I guess sitting it the worst thing for these car.

Any ideas?
RAY

Ray:

When I picked up my '90 last March (almost a year ago, gosh how time flies!!), it too had an issue of the throwout bearing making noise. Didn't happen all the time, and would go away as soon as the car warmed up, or about the 3rd or 4th stoplight. I figured if it didn't go away, I'd eventually have to drop the transmission and replace it. I guess I got lucky, because it eventually went away. I think it just needed a little exercise to limber up some stiff joints. Truth be told, it was probably some corrosion or a burr that eventually got smoothed out.
My car, like yours, sat for most of her first 15 years. It only had 9700 miles on her when I bought her home. It was stored in a climate controlled shop and received the appropriate care, just didn't get driven all that much.
These cars just need to be driven. Often. And they seem to like getting their legs stretched once in a while.

TomC
'90 ZR1 #792

[BBBAD94ZR1]

Thanks for all the input so far, for the record my plugs were pretty black.
Would it be safe to assume my injectors may be dumping to much fuel and loading up after being driven above 4500rpm? Does anyone know a good lt5 tech in NJ. I spoke with Tom Tom and he suffered fRom the same crap.
I also found out the trans rattle is from the car missing and the flywheel weights banging around. Well Im going to get the car scanned in two weeks and see whats going on with my injectors etc.

Any other input is well appericated.
Thanks
RAY