Ls400 94 Tps Question

[lukyscc]

Hi all,

I just replaced my knock sensors and put everything back together. My car idles great! but when i give it gas, right at 1500rpm to 1800 rpm, it starts to die. I check all my connections and fuel line, no problems. I don't have ANY error codes. I read here in the forum that it maybe the TPS (throttle position sensor)? How can you test that? Or can it be something else? I really need some help here. Thanks!!

P.S. I also read that it maybe the ECU but i open it and found no caps leakage. All electronics looked ok.

[steve2006]

When you removed the throttle body the TPS simply unplugs and there is therefore no need to remove it from the throttle body so it should not have gone out of alignment.Did you clean the TB while it was off? Did you allow any cleaning solvent to get into the TPS?

Also recheck all the connectors and vacuum pipes you removed to get to the knock sensors and also make sure the crankcase breather pipes particularly the one under the TB is correctly refitted and secure.

Basically you need to double check the work you have done if all was OK before the job.

[lukyscc]

I did clean the TB while the TPS was connected. Cleaning solvent may have got into the TPS. Can that cause this problem?

[steve2006]

I did clean the TB while the TPS was connected. Cleaning solvent may have got into the TPS. Can that cause this problem?

If it runs down the buttlefly flap shaft it can enter the TPS may be worth blasting a hair dryer into the throttle body intake to dry things out, if you remove the TPS it needs setting up using a special proceedure.

[lukyscc]

Is there a way to test the TSP? Also, can this cause my problem that I'm experiencing?

[landar]

Hi all,

I just replaced my knock sensors and put everything back together. My car idles great! but when i give it gas, right at 1500rpm to 1800 rpm, it starts to die. I check all my connections and fuel line, no problems. I don't have ANY error codes. I read here in the forum that it maybe the TPS (throttle position sensor)? How can you test that? Or can it be something else? I really need some help here. Thanks!!

P.S. I also read that it maybe the ECU but i open it and found no caps leakage. All electronics looked ok.

I think it would really help us a lot if you could back up a moment, Lukyscc. I feel like this thread started out mid-sentence. It left me with a few questions:

1) Why did you replace the knock sensors? Was the engine running poorly before or was it fine? Need a little background.

2) Can you get the engine to go past the 1500-1800 RPM range briefly by 'blipping' the throttle or does it just die when you get to that level?

3) If you bring the throttle up slowly and steadily, does the throttle just get stuck at a certain RPM or does the engine start to stumble and choke?

4) Does it behave the same if you take it out for a short drive in the neighborhood? (ie: under a load?)

It almost sounds like fuel starvation but will wait for your answers to these questions.

[lukyscc]

Sorry not getting back sooner. To answer your questions:

1. Rats chewed the wire and had to replace the wires so I replaced the knock sensor also.

2. It rev pass 1500 rpm if I go VERY slow but if I press on the pedal normally to give it some gas it wants to die.

3. see number 2

4. Yes

So the last month I've been working on it again and decided to take it apart and back track. Well the gaskets I bought were terrible. So i bought new OEM product which were much better made. Now that I put everything back together now it will not stay on or it tries then dies after 15 min of idle. Really upset about this and really need some help :(

Chuck

[fsuguy]

Hi lukyscc,

I'd be very interested in knowing what is causing your problem since I experienced this also. Replaced my TPS (with one from Sewell) since it appeared to have failed (the problem was fixed by this change; for those who are wondering my cruise control stopped working and it was the TPS!).

Did not clean the TB or put anything down any of the openings, but after the change, at around 1500 RPM if I depressed the gas pedal, the engine would want to bog down. If I gradually depressed, it would get up to 1800 RPM, then stumble down to about 600 like it was about to die, then pick up, get to about 1800, and do the same thing. Not sure what the heck caused it or why the problem disappeared, but I don't have that issue any longer (knock on wood!!).