I finally replaced the TPS in my GP yesterday, after it going bad about 3 or 4 months ago. It was reading a full 5 volts, telling the computer I was at WOT constantly. I was getting about 8 miles per gallon. Unfortunately, I couldn't get the damn plug completely off the adjusting screw to be able to adjust the new sensor properly. Spec is .48 volts at idle, and mine is reading .7 volts. I haven't had the chance to adjust anything else on the carb yet. The issue I'm having is that when first started, the car will barely idle, without raising the RPMs slightly, or it will stall. Once it warms up fully, it will idle fine. Other than that, it runs and drives OK. Throttle response and general performance also seem to be a little worse. Everything seemed to come apart and go back together OK, although I did reuse the old air horn gasket. Just looking for a starting point on what to check or adjust. Thanks.
Replaced TPS, now have idle issues
- Thread starter IhaveNoPantsOn
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I know a ton of people out there love the quadrajets, I have had horrible experiences with them. On my 85' 307 had tps and iac problems, same with the 2-barrel on my 84' 231 v6. I replaced them and they got worse. I couldn't wait to get rid of them. Sorry I couldn't help...only helpful thing I could say is replace it with a holley or edelbrock.
Unfortunately, I don't have a spare $300 lying around for a new carb. I really haven't had any problems with the Q-jet, until now.
While .7 v is not an optimum reading, IMO it's not far enough away to cause idle problems. I just had a similar issue with my '87 305, and my problem was poor mileage, along with lazy light to mid-throttle response with the richer mixture. If your problem only occurs during warmup, are you sure that all choke systems are functioning well? I got away with leaner choke settings when my TPS was acting up, but had to re-adjust once a properly-functioning TPS was installed.
Bill
Bill
The problem with this carb is that it was butchered from a great design in order to incorporate the computer carp. That being said, there is a special technique involved in getting the plugs out without ruining the adjusting screw. The way to do it, is to drill in to the side of the carb so that you can push the plug out from behind with a hooked pick. You have to be EVRY careful though not to drill into the adjusting screw, or it will ruin the airhorn. Also, the adjusting screw takes a special tool to adjust it, and that tool is very difficult to find. My advice? Do what I used to do, and take the car to a competent carb shop to have it set up properly. Having it set wrong can also lead the the torque converter clutch not disengaging smoothly, and will cause driveability issues.
Well, seeing as the choke cover is still held on by the original rivets, and it was acting fine before the TPS went bad, I'm not sure it's the problem. But, I will check to see if it needs to be adjusted. It also may just be a coincidence. It has been much warmer since I replaced the TPS, and my car does seem to run slightly crappier in hot weather. Doubt it's the problem, but it may be contributing somewhat.billyjack said:
Don't worry about drilling out the rivets yet, but do inspect your vacuum breaks, as they have the most influence on idle quality during the first minute or so of warmup. Make sure the front break opens the choke about 1/8", and the secondary break opens it to about 1/4". That should put you in the ballpark, and you can fine tune from there.
Bill
Bill
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