raf12690

So... Friday I was returning from the Miami Heat game, and as I go to pass one of many ridiculously slow drivers in the left lane, I feel a hesitation and bogging sound. I was only accelerating lightly, not looking to kick down but gently boost in low RPM to pass, which I do very often and usually it's smooth as silk.

I drive the rest of the way home no problem, but when the RPMs were fairly low and I pushed the pedal a certain amount I got this problem to happen a couple more times.

I have always noticed that my car had a slight jerk in 1ST GEAR when supercharger engages under light throttle. I have a old gen sprint booster and I always figured that had something to do with it. Anyhow I have noticed some noise from my SC pulley bearing (code3) for some time now, but car has driven amazing overall.

It almost feels like the throttle sensor. I haven't tried to press the gas hard yet, but I figured I would connect the old labtop up and see what the numbers are saying.

BTW no code has been thrown whatsoever. It's why I figure it's some sort of sensor. I'm at work so I haven't been able to put up the volume on SCboost's problem video. Will check to see if it's similar when I get a chance.

What say the forum??

scboost

sounds real similar to my issue that I still havnt fixed. when I manually down shift and rpms are about 3k, I don't have the issue. Its in higher gears where you just apply enough throttle to boost but not enough downshift.

raf12690

Well I just listened to your video, and I think our problems are different. I'm having my problem when pressing throttle any more than 5-10%. My car jerks like a kid who was having trouble driving stick in 1st when it normally would engage supercharger clutch. I can drive it with literally a feather foot and it is ok, sound is normal. And it does not feel the same as having no boost, my light pedal can get it up to 45 in no time, I just have to be careful because anymore pressure and I get jerkiness.

I'm going to get to the bottom of it tonight. I'll put a video up most likely as well. Still no CEL or any warning.

scboost

But what you are describing sounds exactly like my situation. I have to feather the throttle as well. Any more and the car starts to hiccup. In the video I was pushing it hard so the hesitation was pulsing fast. But if I slightly press throttle it bucks like a bad stick driver as well

raf12690

Hmmm, I'm scared to give it more throttle so maybe. Do you have a sprintbooster installed by any chance?

scboost

No I don't. I just have EC tune

insame1

what does you IAT read when the car is warm?

scboost

mine is about 130f when all warm. if I get on it hard it will def climb.

raf12690

My IATs are normally pretty low i have a low thermostat and a bunch of cooling mods. Plus it was 65 out. Ive had to replace a faulty pump and it was a completely different feeling. The stutter when first appeared felt almost like a misfire as it first appeared while i was at 60ish trying to pass. I feel it now in every gear as i get to where the supercharger would normally engage. Im going to connect my computer and see what the datalogs say. I cant check for AFR though.

I'll try and record a video and post the logs tonight.

scboost

Other members were suggesting throttle body or maybe even torque converter. I wish I had a star diag

scboost

..

raf12690

So I did a quick log and it hesitated when I gave it a little more throttle. I did a video, but it was not that good and I'm having trouble uploading it. Sound is bad either way, but I felt a decent shake.

Another thing is although I didnt get a CEL, when I went to check for errors an unkown ECU code was showing p0128 (sorry not p0120 )

I'm going to drive it over to my indy shop tomorrow.

scboost

Just keep us updated. im really curious to what they will find.

scboost

Any updates

raf12690

Just got off the phone with the indy. Looks like it was the throttle body actuator. He was having trouble finding issue. He said he'd reset the throttle adaptations and it would run great for a couple minutes then go bad again. The guy put on a used one from a v8 model that has the same part and tested it out to make sure. Said it runs smooth as silk. I gave him permission to put some miles to make sure (I trust the guy). Gonna run 350$ with everything. Would have been 800 or so for a new one so.... Hopefully the issue doesnt return.
Guy is one of the few mechanics I trust. Drives a nasty modded e55.

raf12690

I'll let you know after I drive it some. I'm picking it up later today.

Lenin

If your mechanic cleared the P0120 and it kept coming back then yes, TB is most likely toast. Some of these TBs have sealed electronic components. And even if they are not sealed, they are close to impossible to fix. New or used TB is the answer.

raf12690

Car runs like a dream again. I forgot to post that that p0128 code was the one from before due to the car running in cold weather and it thinking the car wasn't warming up fast enough.

It was definitely a throttle body issue with mine.

raf12690

Try reseting your throttle adaptations and see if it very briefly fixes your problem.

BTW Star garage for the win. Can't tell you the last time I trusted a mechanic like I do them. If anyone's looking for a place in Sofla check them out.

insame1

where?

Lenin

You may be confusing P0120 which is the TPS mulfunction vs. P0128 which is coolant temp below what it should be. Either way, glad you are up and running.

raf12690

Yeah I meant to post it was a p0128 code not p0120. I edited the earlier posts so others won't get confused.
As far as Star Garage it's located in margate/ coral springs.

scboost

raf I tried the sneaky reset. I hope I did it right. the problem was still there but it was much less dramatic. Im thinking the throttle body motor just cant stay steady and is failing to stay open and higher load in higher gears.

raf12690

Yeah I'd think you have the same problem as I did then. If your good with DIY you could buy one online for cheaper and try and install it yourself or get some quotes from shops. You might get lucky like me and they have a used one lying around.

raf12690

So now that I'm up and running, you guys think I should reset my tune? I've never been one to fully understand how ECU adapts with fuel, throttle, etc. You guys think that a problem like this would have affected the ECU to adapt in a negative way while it was bad? Car seems to run great, but I am noticing the car upshifting early even with the Sprint booster. I figure the car adapted a little to me feathering the crap out of her.

Would sneaky reset still work in my situation? I always thought the sprint booster kind of eliminates that issue.