: Midthrottle surge...



eldorado1
06-02-05, 12:45 AM
'96 without maf, experiencing what I would describe as a 'midthrottle surge'. If I have the car in 3rd gear, and am driving at a steady speed... it feels like I let off the gas, and then got back on it! I suspect it may be a faulty TPS, but wanted your guys' opinion... I am running aftermarket plugwires, bosch plugs, and my injectors leak a bit... Sometimes it's a bit hard to start when it sits for ~1 hr (seems to be the magical number), but that's probably due to the injectors.

Ranger
06-02-05, 10:13 AM
Replace the MAF sensor and don't forget the air flow straightener. Why did you remove it? Sounds like a self inflicted wound.

eldorado1
06-02-05, 10:23 AM
I'm running a speed density system, don't need it.

danbuc
06-02-05, 11:02 AM
First thing first, go out and buy the proper AC Delco plugs and wires. The aftermarket wires and Bosch plugs are definitely not helping the situation. If it's a bad TPS, you wouldn't really get a surge at a steady speed. Normally, a bad TPS will cause a surge while accelerating, not while maintaing a constant throttle input. What you describe happening does sound like a possible simptom of a bad TPS, but it also sounds similar to a mifsire, like those that have been seen with after market plugs and wires. If you have access to a digital multimeter, you can try using that to see if the TPS is bad. Just get a paperclip, and back probe the Signal Wire leading from the TPS to the ECM, and then attached the other lead to ground. Manually open the throttle slowly all the way open and then shut (KOEO), and look for any point where the voltage may drop to 0. Normal range on a TPS is about .45v-4.9v, give or take a half a volt here or there. If at any point the voltage does drop to 0v, then the sensor is bad. If you have access to a scope, that would be even better.

So you can get a better idea of what I'm reffering too, here a little picture I made in paint..hehe (Yes, I'm incredibly bored).