annikacarter_

Hey everyone!

I am breaking in my engine sans-turbo and getting the base map set up on my Elite 1000. Motor is a BP4W non-VVT with forged rods and pistons, LS coils with direct fire ignition, 36-2 trigger wheel, ID1050X injectors, FM fuel rail, and a Elite 1000 with the plug and play harness from the car's OEM 1992 wiring harness (engine harness is still 1992 as well), tuning using newest Haltech software.

This past weekend, my AFRs started going all over the place. Between shifts, they would go rich (~10) and then super lean (~25+), and under engine braking were super lean. They will even jump around all over the place when I'm just cruising with very minimal to no throttle input. We are tuning using the fuel film model. The predictive MAP is constantly activating, even when it shouldn't be, and none of our changes are actually causing the expected result. It may seem better for a minute or two, but then it goes super rich or lean again. We have tried essentially everything tuning wise to no avail.

We realized that the voltage reading from the TPS sensor was jumping around like crazy with no input from the throttle and figured that could throw everything off. So I replaced the TPS. With the new TPS, things seemed better at first, but then it jumped back to its original shenanigans. We noticed that, sometimes, when I was not on the throttle at all, the TPS was reading greater than 0% (4% up to even 20%) so I double checked the wiring on the TPS connector to make sure all connections were solid, cleaned the TB to make sure it wasn't getting stuck, and loosened the throttle cable to make sure that wasn't too tight (it wasn't). The TPS voltage is still jumping all over the place, and it is like a hairpin trigger -- if you press the gas pedal down the slightest bit, it suddenly reads 10% throttle. We have tried messing with the ECU filter on the TPS, but it hasn't seemed to make a difference (although, it is my first time tuning with Haltech, so I will be the first to admit it very well could be user error).

At this point, I feel like I have tested everything mechanical that could be wrong, so it must be a setting I'm missing or something! The TPS voltage jumping all over the place doesn't seem right, so I am leaning towards that being the cause of my problems, but I am open to any and all suggestions. Please someone help!

For reference, it is a 1999-swapped 1992 car. I am using the 1999 TB with the 1999 TPS (3 wire... I know the NA 3-wire TPS doesn't work, but I don't see anything saying the NB 3-wire TPS doesn't work...it seems that the NB only has a 3 wire TPS?) and the 1992 engine harness.

redursidae

Have you fixed this issue yet? I figure you've already calibrated the sensor even though you haven't mentioned it?

If the voltage is jumping around wildly with foot off the pedal, it is either caused by a faulty sensor, or noise in the signal/ground. Big contributors of noise can be coils or wideband heating circuits if grounded near/on the sensor ground. Where have you grounded your coils and sensors?

The NB TPS is fine to use, and yes it is a 3 wire sensor. A datalog showing your issue could be helpful to diagnose.

annikacarter_

Not fixed yet unfortunately - haven't had much time to mess with it. I should have a moment tomorrow, so I'll check out the grounds. If I remember correctly, my coils are grounded to the block and the chassis. My sensors are grounded to the block. I will check to make sure the grounds on the block aren't too close together. Thanks for the tip - hadn't thought of that! Fingers crossed. The TPS voltage does fluctuate even with the engine off (ignition on only), so it may not be the coil grounds per say, but could be a different one!

I can see about snagging a log to pop up here. Thanks again