TBIThrottle Body Injection discussion and questions. L03/CFI tech and other performance enhancements.
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This is actually my brothers car, but I really would like to help him out since he keeps spending money to fix things the mechanic says "may" be wrong, but to no avail. I'll just list as much info as possible.
It's either a 1987 or 1988 Camaro with a 305 TBI. First of all, it seems to take a while to start, defenitely a long time in comparison to other injected cars, but may this is just inherant. The car does not seem to have any troubles based on whether it is cold or hot and has power. At any given time, the car will sometimes idle very low when coming to a stop and usually comes back up to normal rpm, but sometimes dies instead. Starts right back up. If in park, you can tap the throttle and sometimes will again, idle way down to almost dying, but seems to come back up. Doing this in gear can cause it to die, the same way it does when stopping at times. Also, regardless of what gear you are in or how fast you are going, if you only give the car a small amount of throttle, it will surge, but letting it roll or giving it more throttle will cause it to run normally. The TPS was replaced(albeit a used one so who knows), unfortunately the mechanic had him replace the ECU, because he felt that was what was wrong, no change, although I think the car runs a little smoother at idle, but problems are same as before. The throttle-body was replaced in the past, due to some sort of problem with the rod the butterfly's are on being all loose and worn, causing a vacuum leak. I keep telling the mechanic (happens to be a good friend of ours, ARGH) that we should have just replaced all the things that talk to the ECU, first, such as the oxygen sensor, temp sensor and what not. Instead, he has decided that we should next take a look at the solenoid that causes the clutch to lock up, he thinks it's sticking, possibly. He also thinks the oxygen sensor (or one of them, however many there are) is lazy and may be bad. When the mechanic hooks the car up to his Modis unit, the only code that shows up will read "Clear Flood" mode, sometimes when putting it in gear and sometimes when fooling with throttle in park. Well, this read is long enough... I can't think of anything else. Any ideas?
I know I might be reaching at stars here...but has the fuel filter been replaced recently? I've seen cars stumbling and stalling at low rpm's, but at increased rpm's smoothed out. Just on a whim I replaced their fuel filter, and then the car ran fine.
Maybe not the same situation, but for a 15-16 year old car, might not hurt. I like to change mine around every 2-3 oil changes, considering how old the car is, and what all deposits might be in the fuel tank.
Good Luck and keep us posted
__________________ - L05 350 TBI, Edelbrock Open Element, DIY Polished Intake, 180º Thermo, MSD Coil, Heater Valve/Air Pump Delete, High Flow Cat,185º/200º Thermal Fan Switch, New Rad, Manual Fan Switch, 350 ANLU Chip, AFPR, FP Gauge, TPI Pump, TDS Headlight Repair Kit, Poly Bushings, 4th Gen Seats
Waiting To Be Installed: Hooker 2460 Shorties, Mufflex 3.5" Catback w/Spintech
Future Work List: 4th gen Posi/Disc Rear, 4L60, Washer Bottle and, Rad Overflow
Originally posted by jconrad I know I might be reaching at stars here...but has the fuel filter been replaced recently? I've seen cars stumbling and stalling at low rpm's, but at increased rpm's smoothed out. Just on a whim I replaced their fuel filter, and then the car ran fine.
Maybe not the same situation, but for a 15-16 year old car, might not hurt. I like to change mine around every 2-3 oil changes, considering how old the car is, and what all deposits might be in the fuel tank.
Good Luck and keep us posted
I second that. At idle the fuel demands are not that high and fuel can almost come to a stop if the filter is to far clogged. I would also perform a full tune up. These cars get neglected over the years. Just for clarification, your brothers car would be an 88 since there weren't an 87 TBI cars and we have one 02 sensor.
No offence, but it sounds like you either have a very lazy or a very uneducated mechanic. One thing to look at is what the engines vacuum is doing. If its old and a bit tired then maybe its not pulling the vacuum that it used to or maybe there is a vacuum leak, or the egr is leaking exaust back into the intake at idle because its plugged with debris. Anything that alters the vacuum with a SD system will change the ammount of fuel will cause excess fuel at idle since the ecm will see map that indicate that the engine is under load when in fact its not. A dirty IAC could also be suspect. If its sluggish itll lag behind the ecms commands and not be where its supposed to be when the ecm moves it. Id sort of guess at this since it goes real low in park. Normally the 88's will only do real speed adjustment of the idle when in drive. When in P/N the idle will remain static so long as its above ~500 rpm and below 1000. Mine usually stayed at around 800 rpm when in neutral with the stock engine. The surging and clear flood mode when the throttle is closed point to possible problems with the TPS that the ecm may not be reporting. Take it to a reputable shop or a dealer thats trustorthy and let them do some diagnostics on it. Make sure you have them call you to tell you what they find rather then just let them do whatever. Odds are its probably something stupid but it could cost alot of money to let them do what they want to. I learned that the hard way when a chevrolet dealer wanted to charge me around 1800 dollars because the pcm threw jsut about every code in the book and they where just going to blindly replace all the bad stuff + the pcm. Problem: stuck egr. I actually had to go over and steal my truck back from them because they where going to go ahead and do the work anyway. Not having the truck anymore helped get some sense into their heads.
Last edited by dimented24x7; 05-26-2004 at 12:02 AM.