stang11

K so I know this has been posted many time but i need some help. I have an 89 gt mustang completely stock besides exhaust and a k&n filter. The car surges and sometimes dies when cold. When it warms up it runs decent but still has a minor loping idle. Here is a list of what i have done so far:

replaced egr valve and sensor
replaced the idle speed control module
cleaned the mass air sensor
adjusted the timing
did a complete tune up (filter, plugs, wires, distributor cap, fuel filter, and oil change)
replaced the tps sensor and set at .97

After all this jazz, suprise suprise itstill surges. It got better after we adjusted the timing and base idle but still surges. The really weird thing, and the part that confuses me, is i unplug the tps and the car idles perfect and drives like a champ. Now why and what would be causing this? Any helpwill be greatly appreciated.

mjr46

run a koeo/koer test and check for vaccum leaks

stang11

yeah did the test on it. got the system to pass but still does it. I don't hear any vacuum leaks but no i have not done a test yet. but why would unplugging the tps make it run good?

9tyfiveo

just a guess, but it might be becuase its not sending a signal back to the ecuto try and compensate for something wrong. correct me if i'm wrong anyone

stang11

I agree with you 100%. I know it's not the tps, but what would unplugging it do. I realize the computer recognizes this and runs off of other sensors to compensate for this.My only idea is my mass air sensor is a little off. Maybe once this tps is unplugged it goes off the temperature and o2 sensors. It's a long shot but the only idea i have.

Seriously the car idles rock solid when it is unplugged, and drives better from start to finish no matter what the temperature is. So i am thinking this eliminates a vacuum leak problem. Could be wrong, but thats what i feel.

Anybody with some ideas? Does the tps work directly with any other sensors or do they all just mesh together to give a final reading?

I8URRICE

could this be a possibility...when it surges it dumps fuel in still causing it to stall / almost stall try giving it a little gas when at idle and see if you could correct the problem and maybe turning down your fuel pressure?

stang11

Possibly. But when the tps is plugged in if i give it gas it sounds like its missing. Not a steady miss but jumps around. If the tps is unplugged it doesn't miss at all.

It does run really rich when the tps is plugged in. Super rich. Would this be the mass air not sensing correctly or the fuel pressure regulator (It still has the stock one on).

TTGreenSN95

take out the ect probe clean it and put it back in or buy another one you have replaced everything else maybe could be the ect probe???should be on your lower intake right side its a longshot but could be it.....I know those things get gunked up so they moved them on the sn95 to the pipe before the TB

Its a fuel multiplyer it reads the incoming air and tells the computer to add more fuel when the air is cold doubt thats it but its worth a shot......either way weather thats it or not you can cross that off your list.

cholericfc

what else have u done to ur car - mod wise??? ...... what kind of computer you have in there?

floodzilla

id also check the fuel system, injectors, rails, etc. everything back as well