Topic: 2.5 tbi ecu failure ?????

[4bangher]

Ok this may be in the wrong area of the site but this is were I have read about some similar problems. my 90 2.5 tbi when the key is turned on no check engine light illuminates not sure if that is normal with these but I thought on all cars it should illuminate with the key on engine off. next it runs for a bit and and then dies air fuel and spark all good but when it dies the idle speed actuator fully actuates a couple of times creating a clicking noise. after reading a few post i've seen about clicking I gathered this may be a common ecu failure. I also have read  about someone replacing their own caps inside the ecu. I would be interested in any info about this i.e. pics of the caps and who else has experienced this and was the ecu the cure.

[Mr_Random]

Ha, quick answer; Renix systems never had a proper CEL. No worries, it aint broken!

The idle speed motor problem may be associated with a number of things; MAP, TPS, or... um I forgot what else. Test them and see... if not you are still planning the mpi swap, right?

[chardrc]

I believe the CEL only comes on when your emitions timer thing hits the time to replace the oxy sensor...

[Castr8r]

The clicking noise you hear is the "Latch Relay" keeping the ignition circut open while everything resets to the "start" configuration.  I would guess that you have a short somewhere in your ignition circut causing it to die.  The "Check Engine" light probably just ain't working.  The ECU in the TBI is a simple computer in comparison with the computer for the MPI engines.  Some people have successfully repaired them, but it's not a job for everybody.  If you put a different ECU in, you will still have the clicking as the relays change settings.  From what I have read, the ECU is  pretty reliable, even after years of use and /or neglect.  Some that were drowned were salvaged by removing to an oven set on low heat (100* to 110*), and "cooked" dry.  I wouldn't blame the ECU just yet.

[4bangher]

Cool thanks for the info the mpi swap is still on I just need to drive this one while I remove the mpi stuff. I will look into some more things it shuts down at different times and really only does it once I start to drive for some reason it will idle and rev for long periods of time and then I get in to drive it and then it dies can't even make it around the block somethings not right.

[Matt vs YJ]

it will idle and rev for long periods of time and then I get in to drive it and then it dies can't even make it around the block somethings not right.

Can you restart it right away by giving it just a little bit of throttle? If so then I would highly suspect that the Idle Control Motor isn't working properly even though it's clicking.

[4bangher]

thanks for the tip I am starting to lean towards the latch relay due to the fact that is will die all of a sudden even with the gas pedal depressed. Also when I go to restart it sometimes it will just crank for a bit then start with or with out gas pressed. I did however monitor spark and fuel while it cranked with no start I had spark no fuel pressure but then the iac would do it thing and fuel pressure would be back and it would start. so I am going to look into a few more things this weekend. all tips are welcome.

[2.5Blues]

I have a similar problem. I also noticed my distributor isnt plugged into anything. i have the 2.5 renix system. I was told the block is from a 95. I replaced alot of parts trying to figure out why it stalls out.

[chardrc]

distributor on renix should just be connected to spark plug wires and the coil (and go into the block to run off the cam of course... ) aka their are no extra plugs for renix 2.5l tbi..

[2.5Blues]

OK theres the 4 spark plug wires and the one going to the coil. that coil on the firewall has 3 places for plugs mine only has 2. The distributor also has a plug coming out of it for pick up. I also got a distributor from the junk yard that has a plug and vacum advance.  The history is it drove home the i day bought it. That night it started stalling out. It goes out of timing when u give it gas. I have tried throwing parts at it to fix. I am confused. thanks for any info

[Mr_Random]

OK theres the 4 spark plug wires and the one going to the coil. that coil on the firewall has 3 places for plugs mine only has 2. The distributor also has a plug coming out of it for pick up. I also got a distributor from the junk yard that has a plug and vacum advance.  The history is it drove home the i day bought it. That night it started stalling out. It goes out of timing when u give it gas. I have tried throwing parts at it to fix. I am confused. thanks for any info

If it has a 95 block, they may have taken the distributor too, which WONT work. If the dist. has a cam position sensor (ie wires coming out from under the cap), then it is wrong.

What year is your jeep? XJ, TJ, or YJ? YJ's will ONLY have either TBI or MPI, XJ can be Carb'd, TJ's will ONLY be MPI.


MPI systems will have a coil attached to the block and no ICU (ignition control module), meaning the wiring harness will plug directly into the coil.

TBI will have an ICU, with an integrated coil. The ICU will have three plugs (two two terminals and one three terminal I believe), one of each should be used, not all three. One wire will be running from the coil on top to the dist.

Carb'd... vac advance, not sure how it works... wouldn't want to touch it really...

[2.5Blues]

Its a 89 tbi. I dont know of anyone who has one to look at. I looked everywhere for a plug and can't find one. I bought a distributor from jw jeeps It has the vac advance and a different plug on it.

[Mr_Random]

what plug are you talking about? There are many of them... I'm sorry more information is needed for me to help.

The distributor will not work, even if it's from the same year wrangler 4.2, it'll fit in the hole but wont do anything for ya.

If you REALLY want it I'll take pictures of the left over pieces of my old system, see if I can help at all.

[2.5Blues]

The plug coming out of the distributor. it comes off the pick up. The one i ordered was for a 2.5 hope they didnt sell me a 4.0. The one thats in my jeep is from the 95 motor that was installed. The only reason i know that is when i ordered a cap and rotor it was different. I took the parts to napa they matched it up.

[Barny]

Sounds like an intermittant short somewhere have a good look at all the wiring esp any that runs near things that move