More problems from Japan with my 86. To update the current string of problems, the rear end grenaded and I replaced it with a D44 with 3.45 gears from a 96. When I did this, the car wouldn't shift out of first. After trying some things, I finally figured it was the tranny governor. While I was waiting on this to get here, I installed my new Accel injectors and attempted to install a BBK adjustable fuel pressure regulator. The bbk piece was a piece of junk (that's the editted word to sub the one I've been using) and broke apart durring install, also damaging the spring/diaphram piece inside the regulator. The car wouldn't hold any fuel pressure and was leaking fuel vapor from the area around the regulator. A new one was ordered along with an o-ring set. After much searching for the proper o-ring set, the guys at scoggin-dickey finally got ahold of the AC Delco bag of o-rings for the fuel rail. This morning, I replaced the o-rings and regulator. When I tried to start the car, the battery was about dead and the only thing I could figure out was that I was leaking gas bad from the rear of the fuel rail near the regulator. After some colorful language, I took apart the intake again and found the culprit, a split o-ring on the crossover tube going into the driver side rail at the rear. Once that was replaced with another new one (i've learned enough by now to order double on things like o-rings), the intake was buttoned back up and a new battery was installed (thankfully under warranty). The fuel pressure is now at about 39psi and it will now pass the leakdown test.
Which brings me to the current problem. The car will start, but not as easily as it should. Once started, the car won't idle. If I keep pumping the gas pedal, it will run and sounds fine. It doesn't rev as quick as it should either. There are no codes present when the car is running, so I don't think its a sensor, although it might be. I triple checked everthing to make sure its all plugged back in. I played with the idle screw, but ended up going back to where it was before since it made no difference.
My best guess is that it's a vacuum line, but I checked all lines to make sure they hold vacuum and they're connected as per a diagram I found on the internet, but I'm not entirely confident that the setup is correct.
Any suggestions would be greatly appreciated at this point.
Also, if anyone has a good vacuum diagram, I would really appreciate it if you could scan it and email it to me. My address is csavaglio@hotmail.com

Thank you all for the help.



[Modified by okinawa86vette, 5:51 AM 9/20/2002]

 

I am sorry for asking a dumb question but......... do you have the tube from the TB to the MAF hooked up?........ is it in good shape?........ that would cause the exact thing you mention....... guess how I found THAT one out...... :seeya

 

No dumb questions when it comes to my car, especially after the 16 yrs of Japanese service before I got to it and "saved" it. The intake hoses were all hooked up and the maf was plugged in.
Between me and one of my carburetor friends are pretty sure it's a vacuum line not hooked up correctly, but again, we're not 10 percent sure.
Thank you for the suggestion.

 

Usually when you get a crappy idle its the IAC valve. Take off the TB, clean it again, disassemble and clean the IAC.

Then check for a vacuum leak, check to make sure all your injectors are firing (accel's have a bad rep), check all plugs and wires, cap and rotor, and finally the MAF sensor and its relays.

 

I'm having similar probs. right now. What I've learned to check for vacuum leaks:
My mech. used some kind of propane to check it, when he ran over a leak the engine will idle up.
I have used carb. cleaner and sprayed the lines before with the same affect
I have also heard of slowly running from a hose or pouring from a cup water onto the vacuum lines and when you hit a leak the car will choke and die(never tried this though).

Finally got mine to idle but now am having oposite problem (see other post if you like).

 

These kinds of problems are a real PIA to track down. Unfortunately, there is no quick and easy solution to your problem.

It boils down to a matter of checking every possible thing one at a time. Check the easy stuff first before diving into the tasks calling for a lot of work, like pulling the plenum and runners again.

The plenum runner gaskets are 'SIDE SPECIFIC" and if you mistakenly installed the left side gasket(s) on the right, you'll get the problem you described. I believe the lower ones are the worse offenders.

I had a similar problem a couple of years back and after going through so many, many checks and days of making sure everytihing was 'right', I finally got to the point of having to pull the plenum and runners.

After checking the obvious, I used my computer troubleshooting techniques and recalled what I'd changed. In other words, the engine ran fine, then I changed something and then the problem began. So I went back to a point when everything was fine and low and behold, I found that I'd mistakenly left one of the injector "O" rings in the intake when I installed the new injectors.

The doubled "O" ring caused a vacuum leak and when I removed it, and reinstalled the runners and plenum, problem was solved.

Your problem may not be caused by this, so here's what I'd do.

I'd first make sure that all the sensors and working properly. I make sure the TPS voltage is correct, the IAC is clean and reset using the GM recommended procedure, ignition timing, etc.

I'd unplug the MAF and if the idle improves, then the MAF is bad. I had that problem a few months ago when my idle went south and unplugging the MAF smoothed it out. When I tried a friend's MAF from his 85 the engine ran perfectly, so I bought one off a wrecked Vette. In my MAF case, there was NO CODE either.

Off the top of my head it sounds like a vacuum leak. Sometimes the vacuum hose on the underside of the throttle body is missed; sometimes the EGR vacuum line, etc. Sometimes hoses are brittle and cracked and will leak. Crossed plug wire can cause idle problems.

Like I said, there's no quick and easy solution; just a matter of going over everything with a fine tooth comb.

Let me know if I can help further.

Jake

 

Thank you for the ideas. I'm pretty sure its a vacuum problem too, and I know the car's vacuum lines were improperly run when I got the car. I'm trying to get things sorted out, but can't find a complete vacuum diagram in the shop manual, just the one or two that Sharky suggested. He's going to send me pics of the routing, so hopefully that part should be sorted out soon.
One question though, how many lines are supposed to come off the throttle body? I know of the large one that goes to the valve cover and the small fitting that goes to the egr solenoid, but I keep seeing a third fitting on these diagrams, and I don't recall there being a place on my t/b for it.

 

Ok, I assume (?) you have the two pass side rear small vac. ports accounted for. One is for the FPR and the other is for the interior HVAC ducting feed.
Then there is the power brake booster line at the back of the driver's side of the plenum.
On the bottom of the plenum is the IAT sensor.
On the RH side of the TB, there is a large fitting for the right side valve cover breather via a metal line.
There is a small vac port on the under side of the TB, on the driver's side, but as mine is capped off, I don't remember what that goes to. And that should be it for the TB.
On the intake manifold, driver's side, there is a port that supplies vac. to the left side valve cover PCV and also feeds the fwd canister through an aluminum tube.
BTW, my cold start injector port always needs to be fiddled with to seal properly every time I disassemble the intake.
If you replaced the TB, check to see if you have the correct TB to plenum gasket installed. There are two different styles of TBs on the L98s and you can't interchange the gasket between them. I believe that the difference is that the earlier TBs had a triangular opening at the lower part of the TB for the IAC, and the later versions did not...I think....something to check.
I hope I didn't forget anything... Good luck.


[Modified by lowflyer, 6:11 PM 9/21/2002]

 

Ok, all the ports are accounted for, now I just have to figure out the routing for the port that is capped off on yours, the small driver's side throttle body port. I keep seeing it in the diagrams tee'd off to the egr sol. and then down to some of the components down in the front driver's side corner. I think this is the source of the problem.
I didn't think of it before, but there is a small hotrod shop/american car dealership accross town that usually has a few c4's. I'm pretty cool with him, so he shouldn't have a problem with me poking around under the hood of one of his cars.
Thanks for all the help. Hopefully this will get sorted out soon.
Keep any suggestions coming
Chris

 

In the mean time, you can just cap it off to see if it is the problem or not. But honestly, I don't think there is enough volume of air that can get by there to account for a motor not wanting to idle. It is a very small port. At worst its gonna run the idle high...Good luck.

 

That port isn't just open right now, it is routed to the egr sol. Supposedly, it's supposed to T off to the egr sol and down to the charcoal canister stuff. I've seen even minor vacuum leaks cause a car not to run at all, so anything's possible when it comes to vacuum lines.

Chris

 

Actually I just pulled my cap off and ran the car, and it hunted for an idle until it settled alittle high... but some cars react differently to things...I think you have other problems...
Too bad you are so far away, my uncle owns and operates Sato (Jidosha) Automobile Repair outside of Yokohama, he could help you out. He does some US cars, but I did had to walk him through a Q-jet rebuild before:)

 

Well, after using Sharks pics and a C4 at my friend's shop, I have all the lines hooked up the way they should be. It still shows the same signs, hard start, has to be revved to keep it running, etc.
I pulled one of the plugs and found it to be fouled pretty bad. Would this cause the problem? I'm pretty sure the plugs got fouled when I was having the fuel reg problems, only getting an eratic 20psi.