Hi folks,

I just picked my car up from my mechanic after months of dicking around and it has an issue where under boost (around 3,500 - 4,000 RPM) it will hesitate/sputter. The idle is also a little high 1,100 RPM but only after being driven. When I start her up idle is about 800.

I have been reading up on this issue and decided to disconnect my TPS in an attempt to see if the condition gets better or worse.

I disconnected the 3 wires and reset the ECU - there was no change to the way the car drives. The markings on the TPS say 89 ewt-h8e and does not look like the picture of a TPS on rockauto. (see pic below)

There is no CEL with TPS connected.. but with it disconnected there is.

I do not have a multimeter and thus can not check the TPS as per vfaq.

Do you think my TPS is the problem? or at least part of it...

I have had 2 different garages remove all boost leaks
Compression is 145+ accross the board
Boost is at factory setting
16G turbo
ECU has no visible issues
Walbro 255 and aeromotive AFPR
Stock MAFS



EDIT: Looks like I definitely have an 89 TPS I wonder if my intake manifold is from an 89 too /ubbthreads/images/graemlins/uhh.gif

EDIT: I bought a new TPS (after buying a '91 VR4 tps and then a '90) I now know that I have a non-turbo 89 TPS - should have just taken the part in to NAPA when I went the first time..

Subscribed. My car does the same exact thing. I just replaced the idle switch and the only difference I noted was that the car doesn't lose idle and almost die anymore. I still have the sputtering issue and high idle though. Does your factory dummy boost gauge peg out under light acceleration? Mine does this where it didn't used to. Next on my own list is to pull the MAF and clean it and then maybe pull the turbo and inspect the WG and the turbo to see if there are any cracks. It is driving me infrackinsane though....

this thread may help click I've been chasing this issue for a while and started the new thread specifically on the TPS questions I had.

My factory boost gauge acts as it should (I think) I have an aftermarket boost gauge so I don't pay much attention to it.

i had a similar problem, however my CEL would turn on randomly, i replaced my knock sensor and its totally fine, i did think it might be a TPS issue and i did order one but never ended up using it. if you can, i suggest reaching back to the knock sensor and just checking to see if its maybe a little bit loose

Cool. Is the knock sensor on the back of the motor? Underneath the intake manifold?

yeah, see pages 7 and 10 of this doc.

Also this is a handy thread on the knock sensor

Thanks, I'll check that. I pulled off all my intake tubing from the filter to the turbo and cleaned everything. There was oil at the lip of the turbo inlet and oil coating the tubes, but there was ZERO shaft play on the turbo. ??? Anyway, I also pulled the stock MAF and cleaned it up really good with some MAF spray. Reinstalled everything and no change. I'll check that knock sensor. What would be next to check??

The oil at the front of the turbo is a result of the suction from the valve cover. Has nothing to do with the turbo itself. It will slowly pull oil out of the valve cover breather and send it into the intercooler pipes. The way to verify this is the case is you will not see oil on the filter side of the breather hose inside the turbo inlet pipe.

Hesitation could be due to a countless number of possibilities. Plugs gapped to high will cause cars to "Skip-fire", my words, under boost at high rpm. Any sensor which monitors the position of anything can cause this. On some cars, not necessarily Galants, if the TPS reads a value above normal, it will set the car at a default max RPM. Subaru's do this if you remove the throttle stop at the bottom of the gas pedal on the FBW throttle bodies.

You could have bad spark, bad air metering, bad fuel metering, bad fueling, bad sensors, and on and on. It is very hard to diagnose problems such as these due to the myriad number of possibilities.

So whats a person to do? Step one. Rule out things. Any new items or known good items, rule them out. If you can replace parts with known working, even better. Step two, start obvious. Look for things you can inspect and check without dropping a dime. Frayed wires, bad grounds, loose connections. Step three, process of elimination. You say the car runs the exact same with the TPS connected and disconnected? Good chance it ain't the TPS then. If you change something or a change makes no difference, it's probably not the problem then. The only time this doesn't really apply is when it is purely electrical. Missing the chassis ground ofr a host of sensors will mean none work, but the car may still run. And it might be all of them contributing to the problem. Fortunately, this almost always results in a CEL.

You definitely have an older TPS. Might be time to think about getting a 1G NT throttle body, with a working TPS, just to put that on the ruled out list.

/brox

Someone local to you has to have a multimeter. Maybe the local auto parts store has something that can test it.

If you do find someone or something to test it, and it tests bad, 25 bucks ain't that bad.

click

After I ditched the old vpc safc combo and went to ECM tuning v3, at first start up I experienced erratic idle. I shut the car off and then tried to restart and nothing. ECM software stated the tps was the culprit. Sure as sh*t tests confirmed this.

My iac was also bad. Check that while you are at it.

click

I have bought from both of these merchants and received good working products in a timely manner.

Thanks for the replies guys. This problem is so frustrating! When I have more time I'll be looking at that knock sensor. I'm an electrician, so a multimeter has been in my repetoire for a number of years. I tested the coils on that idle deal and they all tested at 32 ohms. The hesitation is so damn erratic though. Under light loads it will almost always peg the factory boost gauge, but if I let off the throttle completely and get back into it, sometimes it will peg again and sometimes it will boost full and the gauge might come up 1 or 2 lights. I just don't get it. Something has to be screwed up, but figuring it out sucks!! The car runs all the time right now and still gets good mileage and I know it's going to be something stupid, but I just don't have the time to mess with this for hours and frackin days to figure it out!

get a logger

its the only way to troubleshoot these cars.

anything else is just guessing /ubbthreads/images/graemlins/dunno.gif

Definitely want to put a logger on that thing. I fought with TPS nonsense for months before I broke down and spent about $30 or so on the cabling to run MMCd or whatever on my netbook. Within a day, I saw this.



This was taken at idle after a drive home. Everything was well up to operating temps (ran fine when cold). What's the ECU supposed to do when MAF reports idle and TPS reports WOT?

You can see my TPS was reporting WOT at idle, changed its mind, the engine stumbled, and then died. I dealt with this every time I'd use the clutch during my 45 minute commute after work in the heat. Fuckery.

I bought a multimeter and tested/adjusted the TPS as per the "1gs_tps_complete_info" doc.

I am getting .5v between the green-blue and green-orange wires and an OL with any other configuration (GB-GR, GR-GO) is this bad?

Also tested my ISC and all were at 30ohms

Knock sensor looks good too...

...looks like I should get a logger.

Farfick where in Ct are you? I could let you use my logger tp try and find the issue.....

Willimantic how about you?

You should have .5v between connector points 2 and 4. These points are, on the connector, the one that is alone on the end(4) and the one that is in the middle next to the gap(2).

Those pins correspond to (2) Sensor signal(To ECU) and (4) Sensor ground. Pin 1 should be a 5 volt reference signal.

Check Continuity to ground and that you have a 5V reference signal with the key in the on position. Also, moving the position of the TPS mechanism should result in a change to the voltage.

/brox

Just checked the above and it all tested fine.. I have already ordered a replacement TPS so I'll probably throw it on anyway because race car.

Quote:

You definitely have an older TPS. Might be time to think about getting a 1G NT throttle body, with a working TPS, just to put that on the ruled out list.




I just ordered a 1G NT Throttle body with tested TPS ISC and closed throttle switch. Fingers crossed

Im having a similar issue. As for my high throttle, I loosened up the throttle cable and that fixed that. This issue is out of nowhere though. Nothing has changed on my car and all of a sudden it is cutting out like you stated. I have noticed that if I ease into the throttle before hitting wot it will not cut at all. Maybe yours does this too? I will also note that my boost has increased and im not sure why. I have an aem truboost controller and it wont turn it down at all. I have even put the vac line from the wastegate directly to manifold pressure and the boost is still high (18psi) I understand boost creep and stuff but this is all out of nowhere.. Is your boost different at all on your actual boost guage?