hard start + idle searching ...?? - Team Camaro Tech
Troubleshooting Diagnosing problems done here.

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post #1 of 20 (permalink) Old Nov 8th, 01, 09:03 AM Thread Starter
 
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Location: Buffalo, NY
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Hey all. Anybody ever get these two problems caused by the same thing or do I have two different things wrong? So far I've double-checked all vacuum routings, checked the TPS, completely tore apart & rebuilt the TBi (injectors included), and checked all fuses/wiring. The EGR looks like it's ok but I'd hate to go buy a new one just out of curiousity. I'd also hate to think it's a lower manifold leak, but hey if that's what it is, then at least i found the problem. Thanx for any help
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post #2 of 20 (permalink) Old Nov 8th, 01, 09:13 AM
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What is your fuel pressure?Should be 9-13psi.
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post #3 of 20 (permalink) Old Nov 9th, 01, 07:02 AM Thread Starter
 
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<BLOCKQUOTE>quote:</font><HR>Originally posted by sschevyfan:
What is your fuel pressure?Should be 9-13psi.<HR></BLOCKQUOTE>

oops- oh yeah, i forgot to mention I have been wanting to check that but nobody I know has a pressure gauge. I might just have to go pick one up. The injector spray looks normal, but I guess fuel pressure is probably one of those things you can't tell by looking... ?
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post #4 of 20 (permalink) Old Nov 9th, 01, 04:42 PM
 
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that problem ,hard start yeah .
tps,fuel pressure ,fuel pump relay sticking.
ignition coils/module,oil pressure send switch,sticking i.a.c bad wires,plugs
timing chain play ,flooding injector.
fuel pressure regulator leaking down.
gm is famous for this problem..........

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renny calisti
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post #5 of 20 (permalink) Old Nov 9th, 01, 04:43 PM
 
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that problem ,hard start yeah .
tps,fuel pressure ,fuel pump relay sticking.
ignition coils/module,oil pressure send switch,sticking i.a.c bad wires,plugs
timing chain play ,flooding injector.
fuel pressure regulator leaking down.
gm is famous for this problem..........

------------------
renny calisti
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post #6 of 20 (permalink) Old Nov 11th, 01, 08:33 AM Thread Starter
 
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Thanx for the replies I got new plugs/wires/cap/rotor/coil just for the **** of it, they all kinda needed to be done anyways. I checked the EGR & solenoid, got a new EGR gasket, the TPS looks ok and oil pressure looks good (no drops). I'm going back out there now to check the fuel pressure/regulator, IAC, and measure the oil press sender. Hope I find something soon...
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post #7 of 20 (permalink) Old Nov 12th, 01, 08:21 AM Thread Starter
 
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Ok, so when I disconnect the MAP sensor, the idle straightens out, but it's still hard starting. I replaced the sensor with a good one, and it went back to hunting. Manifold vacuum at idle is pretty steady around 20Hg, which should mean no vacuum leaks, and fuel pressure from the pump is about 11.5 psi. Could a bad or weak distributor module cause any of this? I'm almost out of ideas here... HELP!!
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post #8 of 20 (permalink) Old Nov 12th, 01, 10:16 AM
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It has been a good long while since I have diagnosed something like this but lets see. Your car should have an IAC motor (idle air control) I remeber having problems with them and one "fix" was to remove them (carefully as they are rather delicat) and clean out the opening with a good carb cleaner. I know there is a simple test to perform on them but I don't remeber the procedure. perhaps someone on here would know. There is also a way to adjust them. Also clean around the throttle body and wipe out the air horn and inside the plenum as good as you can with a lent free cloth and carb cleaner.
I remeber working on a car that had the vacuum port to the egr plugged up and it caused similar problems. --hope this helps in some way.
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post #9 of 20 (permalink) Old Nov 13th, 01, 10:58 AM Thread Starter
 
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Hey again. When I rebuilt the TBI I took the IAC out and cleaned it up pretty good. Last night I disconnected it altogether and it still had both problems. I figured the idle would be just too high or low with it disconnected, but I don't see how it could surge like that. I'm gonna try and check the alternator and EST/ESC modules, then if still no luck I guess I'll have to get an IAC & see what that does. Thanx for the help
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post #10 of 20 (permalink) Old Nov 14th, 01, 08:23 AM
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Hey I just thgouht of something --does your car have a MAF (Mass Air Flow) sensor located in the cold air induction tube? if it does get the car started and try just squeezing it and see if it makes a difference. Also try tapping on it. We used get a lot of cars with bad MAF sensors and that was how GM had us diagnos them. Although on reflection they were usually on 2.8 v6 engines --might be worth a try. tyr the same thing with the MAP (Manifold Absolute Pressure) sensor. Also check to make sure you have manifold vacuum to the MAP sensor -very important!

Is your computer setting a code during all of this?
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post #11 of 20 (permalink) Old Nov 14th, 01, 08:57 AM Thread Starter
 
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Nope- no MAF sensor. I've tried 3 different good MAPs- that didn't help. Last night I swapped in another ESC module, tried an old spare PROM chip, disconnected the knock sensor just for the **** of it, still no luck. I screwed around w/ the timing & got it running UNBELIEVABLE, but it STILL had the surge at idle and still hard to start. At this point it almost HAS to be the distributor- I figure it's got to be something electrical because it runs ok with the MAP out of the picture & I've tried everything else it could possibly be. Anyways we're gonna try & hit the boneyards Saturday and try to find some spare parts. Ever notice it seems only 'car people' have these kind of problems?
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post #12 of 20 (permalink) Old Nov 14th, 01, 09:07 AM Thread Starter
 
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ps- oops i forgot, yes, the MAP's got the right manifold source. When I rebuilt the TB I was sure to clean out all the passages (I would literally eat off of the TB), and I replaced all vacuum lines. When the MAP vacuum port is disconnected, it gives a code 34 I believe, and when the electrical connector is disconnected it gives code 33 (unless I have the codes backwards)- either way I verified them in the manual at the time and they were both right. If this turns out to be the distributor I'll be soo happy...
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post #13 of 20 (permalink) Old Nov 14th, 01, 12:01 PM
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well --I'm out of ideas --it is pretty difficult to diagnos over the forum. Good luck !!
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post #14 of 20 (permalink) Old Nov 15th, 01, 11:18 AM
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greetings lowaholic, I hate to ask a dumb question. But what year is your vehicle, what size engine, and what specifically are the malfunctions that you are experiencing. Are you getting a check engine soon light and if so, what are the codes that it displays? need this information to give you a better answer to your problem.
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post #15 of 20 (permalink) Old Nov 17th, 01, 05:55 AM Thread Starter
 
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Hi again. It's a 1990 5.7L TBI. It's very hard to start hot or cold, and it 'hunts' for idle but never finds where it wants to stay- it would probably do this for hours if left alone. The only codes it gives is 33 or 34 when the MAP sensor is disconnected (depending on where it is unhooked- vacuum or electrical). The idle straightens out almost completely when the MAP is disconnected, but it's still hard starting. I've replaced the MAP 3 times with no change and also:
-new plugs/wires/cap/rotor/coil
-new dist. module
-rebuilt TBI & cleaned injectors
-checked fuel pressure, 11.3psi
-checked & cleaned EGR
-tried a different ESC module, no difference
-performed vacuum test, all looks ok
Thanx again for any help
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