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

[WB9MCW]

I still suspect the fuel pump(it very well may be the injectors are shot but lets check the fuel psi first)...do the psi test on it and change the ff like tt said.... next will be the ohm's on all 8 injector readings....go to this site for ideas and pic's..plus jeffvette is good at zr-1 diag. so work with him on it but be sure to do steps one at a time and keep reporting here what you find as u go! Here is the PNW ZR-1 site url... We all know how you feel right now but not to worry the brotherhood will get you through these times. Right BlackJack!!!

And I quote the master!!!

LT5 Top End Tear-Down

By:

Jeff Flint - Washington State Director/ZR-1 Net Registry
Robert Melbo - Oregon State Director/ZR-1 Net Registry



Looking under the open hood of a ZR-1 can be a scary proposition. Lines run every which way and the possible expense of a misplaced screw or broken part can send shivers down the spine. What looks to be a nightmare is actually quite simple in reality. Part 1 will look at the removal of the top end, while Part 2 will focus on the cam covers for refinishing to bring new life to the engine.

http://www.pnwzr1.net/

[blackjack]

right on
blackjack

[tomtom72]

Jez Ray, bless you for draining the tank! Go buy a fuel filter and use that to get the wrench size for the nuts on it and the lines...I don't remember if they are the same, sorry. Swap the filter, and do a pressure test alla the book flow chart or see Jeff's answer to Nate(sick 90) for a simpler way.

Gotta start eliminating places to look. If the fuel sys check out then ing sys is next on line. I would still say that if the fuel sys checks out okay I would borrow a scan tool and "look" at what the motor is doing. You can take out all the plugs and turn the key to "on" and smell all the plug holes...if the injectors are leaking you might smell the fuel or just turn the key on for a short time and then pull the plugs to see if gas is present. Obviously it shouldn't be and the injectors are leaking.


Tom