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trinity5007

Rough idle won't rev up

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Ok so sorry if there is a page on this already. I tried looking i couldn't find anything. Here is my problem tho. I have a 1989 jeep comanche. I love this thing wouldn't trade it for the world. It's 400000 k on it. So being that the engine is high mileage I decided time for an upgrade. Rings were starting to go it was having trouble starting so i thought. It was time. I have a 4.oho sitting around I thought might be worth to throw it instead of another 4.0. So I rebuilt the ho new bearing new rings new pistons. Head was redone. It got the works. Slapped it into the truck. Now it idle like a bag. And refuses to rev up. Just pops and backfires. I have checked the timing to make sure the cam is good. It's where it's supposed to be. It's got new o2. New distributor. New cap rotor plugs. New map. New tps. New fuel pressure regulator new ecu. New injectors. New temp sensors. I double checked all grounds. Removed them cleaned them and reinstalled even added an extra ground for measure. I am and at Los as to what could be causing my problem. It still has the renix system in it. I do have to system for the engine but don't want to pull it but I will if I have to. Also the engine is out of a 92 both 5sp standards. I did the research from what I could tell the block is the same just heads and sensors are different. I put removed the 92 sensors and installed the 89 sensors. So everything should work. Any help would be greatly appreciated. Google the crap out of it. Seems it's an issue but no one has a solution.

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Which intake gasket did you use? For the Renix or the HO?

Needs to be for Renix.

 

I know you think the timing is right, but bear with me. 

 

Using Tips 12, then 13 at www.cruiser54.com. Double check it. 

 

Tip 17 covers the exact swap you did. Read it. If you used the 92 flywheel/flexplate, that could also be your issue. 

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Sorry. I use renix flywheel but ho intake gasket. I did compare them before putting it toger. they looked the same but i could be sucking in air if they arent the same. Didnt even cross my mind till now actually.

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Ok so the only thing i did wrong was the intake gasket i used the one for the ho not the renix. Mmm. Also worth noting i have to ho exaust system on it. But intake has been gorund in the correct plases already. I know its not the problem it was on the old renix for six months prior and never had an issue. I'm going to pull the intake off and double check the gaskets . I set the time exactly how they say. Not exactly my first time working with engines. Lol ill see how it goes

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Exhaust system doesn't matter. You must use the  gasket for the intake manifold you're using. 

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Ya i pulled the intake off last night. Way different. I'm not sure how i missed it. Going to get a new renix gasket sent over today

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I think I'm going to cry. I pulled the intake off. Put in the proper gasket. Put it all back together. Now its flooding bad. Checked wires sensors. Everything is good. I did find a crack in the intake so had to replace it. I don't know what to check. And i don't want to take it to a local dealer. Because frankly i don't think they have a clue about these trucks anymore.

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Checked and replaced. Altho when i was setting the tps. It had 4.82v coming from ecu. I was checking comtonuity and resistance readings from temp sensors at ecu plug decided for giggles check out reading from tps. I have return reading to ground but no supply from ecu going to tps. I'm wondering now if there is broken wires in the harness

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Checked and replaced. Altho when i was setting the tps. It had 4.82v coming from ecu. I was checking comtonuity and resistance readings from temp sensors at ecu plug decided for giggles check out reading from tps. I have return reading to ground but no supply from ecu going to tps. I'm wondering now if there is broken wires in the harness

Are you using the flat 3 wire connector at the TPS or the square 4 wire connector to test?

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Lol sorry when i first set the tps i had proper voltages. And readings. Then i had to pull the intake off and replace the intake gasket with the proper one. Had to change the intake out for a different one because the old one was cracked. After putting the new intake on. I reset the tps. But the refference voltage was 4.82 instead of 5. Test ran any way. It sounded like the ecu wasnt getting proper readings from the temp sensors. So i pulled the plug from the ecu. And was checking the readings from sensors. I then checked resistance and continuity from the tps. At the ecu plug i had a high resistence from the ground to input signal. Wich makes sense given throttle was closed i then checked ground to refference line i had an infinate reading. Meaning no connection. I then check continuity on those same line. I have no connection. From the ecu plug to the tps on the reference line out. If that makes sense. I'm figuring moving wires around might have broken one or more.

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On ecu plug 15 pin connector, number 3 on left row is ground, pin 7 on right row is tps input, pin 15 on right row is tps 5 volt supply. Testing pin 3 to 7 shows 2mohm resistance. Testing pin 3 to pin 15 shows no connection, infinite resistance indicating no connection. 0 continuity. That's best I can describe it. I'm not sure how to upload pics. But I found the fuel injection manual for jeep renix engines. So I have been going through it to get a better understanding of what everything does. And how the sensors react to help the ecu.

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Ok so uptdate i pulled the ho out and slaped in another renix 4.0 i have runs perfact. So whatever the problem is or was is in the engine itself not the wiring.

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At least test the CPS. II bought a new one and that was how mine was running. Till I tested and replaced it.

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