884x4

Well I took a road trip in my 88 xj 264k auto tranny 4x4
It was a 200mi trip so I topped off my fuel and was on my way.
I was running about 65-70 most of the trip and here's where the problem is, the RPMs would not go under about 2600 unless it was under 50mph. Most of the trip it was at 2750? That isn't normal is it? I figured it would run 2200-2500 at 65.
I have 31x10.5 tires and 4.5" of lift.
It also struggles to shift into 4th. I have to be running over 2000 RPMs for quite a while before it will shift into 4th
Could it be a failing TPS?
Thanks guys

cruiser54

Yes, it could be.

Could also be too much resistance in the sensor ground circuit, poor grounding of the engine management system in genersl, poor conductivity through the C101 connector.

Click on the Pink Link in my signature and do the procedures outlined in posts 1,2,3,5, 10 and then 8.

884x4

I have some of those already, but I will do them again.
I have a question in the first one about the dipstick grounds. My battery cable goes to that one and it is not actually a stud on mine, it's a bolt
See here




Is this right? I cleaned these after I took the picture

cruiser54

That's fine as long as it's CLEAN and SHINY.

What have you and what have you NOT done so far?

884x4

Adjusted TPS(2 months ago), cleaned dipstick stud grounds, the connector over brake fluid reservoir(2 months ago), clean throttle body and IAC, new cps(2 months ago from autozone) I think the cps is failing again because it was bucking a little and dying randomly yesterday(ill buy from NAPA next time, also the fuel pump has a loud wine now after my trip so I think that's about to go, another thing is my RPMs will shoot to 3000+ then drop down ever couple start ups, that's another clue to failing TPS correct?
That's all I can remember so far

cruiser54

Sounds like the TPS is going out on you.

Ever do the sensor ground test or check your CPS output?

#5 and #7 in my link below.

Hopefully, you did everything in #1 and also go ahead and do #3.

884x4

That's what I'm thinking too, is NAPA a good choice? Lord knows I'm not getting it from autozone. And I did do your cps test, I was getting .1 DC volts so that's crapped out. I did do all of 1 and I will do the others tonight.
Thanks

cruiser54

AC volts, my friend....

Napa is fine. But do the sensor ground test first.

1991Jeep_Man

[Threadjack..]

Haven't poked fun at Cruiser for a while. OP, your problem is it's a Renix. Promptly sell and buy OBD I, problems solved forever.

Poke poke, prod prod. [\Threadjack]



Lol, I am very much kidding. Cruiser is very knowledgeable of da Renix as I am sure you noticed. Follow his advice, your Renix shall live another lifetime.

cruiser54

Hey, to me any attention is good.....; LOL.

884x4

Hahaha that's a good one, either way I will never get rid of my xj and will do cruiser thanks

884x4

.1 ohms on the sensor ground test, didn't budge when wiggling the c101 or wiring harness. looks to be tps

884x4

hey cruiser,just for fun I decide to do the tps adjustment. but this time because I did engine side last time, I did tranny side this time. so my reference was 4.72 and the output I got was 3.6, so I adjusted it to the 3.91 it was supposed to be.
I decided to test engine side, and now that I adjusted tranny side, the engine side is off by .2 volts. is there a trick to making them match? or does this prove my TPS is bad? thanks

cruiser54

They'll never match. I always use the engine side for adjustment because the ECM is more finicky about it's input than the TCU is. I only use the trans side when diagnosing shifting issues.

884x4

Ohh alright, Well it seems that adjusting the tranny side did not fix my issue