I know ECU's "nearly" never go bad, BUT...

...at what point do you give in and believe that you have a bad one? :dunno:

I have replaced...

• IAC (twice)
  TPS
  MAP
  o2 Sensor
  EGR valve

I have VERY thoroughly cleaned the throttle body as well as cleaning the the fuel system with Seafoam and the IAC still wants to stay open and run the engine at 3000 - 3500 RPM. I have run the FSM tests and the IAC is good. The EGR valve is not working even though it is brand new (Mopar).

The EGR solenoid has vacuum running through it all the time no matter what which tells me from the FSM testing that it is bad, but I am not sure I believe that. I am really starting to believe that the ECU is gone as I just can't believe that all of these things that are controlled by the ECU have gone bad at one time.

I managed to get the IAC to close and as soon as it did I unplugged it so it would stay shut. I took it out and drove it around for a while and everything works fine as long as I keep it disconnected :roll: .

Any insight or experience...?? I'm tired, pissed off and about out of ideas. I have already spent too much time & money trying to fix this, but it seems to me that I am in for another $200...

...at what point do you give in and believe that you have a bad one? :dunno:

 

I have replaced...

• IAC (twice)
  TPS
  MAP
  o2 Sensor
  EGR valve

 

I have VERY thoroughly cleaned the throttle body as well as cleaning the the fuel system with Seafoam and the IAC still wants to stay open and run the engine at 3000 - 3500 RPM. I have run the FSM tests and the IAC is good. The EGR valve is not working even though it is brand new (Mopar).

 

The EGR solenoid has vacuum running through it all the time no matter what which tells me from the FSM testing that it is bad, but I am not sure I believe that. I am really starting to believe that the ECU is gone as I just can't believe that all of these things that are controlled by the ECU have gone bad at one time.

 

I managed to get the IAC to close and as soon as it did I unplugged it so it would stay shut. I took it out and drove it around for a while and everything works fine as long as I keep it disconnected :roll: .

 

Any insight or experience...?? I'm tired, pissed off and about out of ideas. I have already spent too much time & money trying to fix this, but it seems to me that I am in for another $200...

Brent,

Have you checked out this fellow yet? Besides Pete or Eagle I haven't found a whole lot more information about RENIX electrical issues.

http://www.lunghd.com/Tech_Articles/Eng ... ostics.htm

I have a new coolant temp sensor, but I have not yet installed it. I was going to try that before spending the money on an ECU, but I wanted some other input if anyone had it.

Thank you for yours and for the link... :cheers:

i have come across a few bad ecu's over the years and its always frustrating because its the last thing u would expect and it always comes after u have thrown some serious cash at the vehicle or at least alot of time in chasing wires. the one thing that has been comon in each of my bad ecu cases was i had no comunacation with the ecu either with a scaner or the traditional jumper wire test . my advice is price the ecu and if it is reasonably cheap buy it and give it a try , now i know throwing parts at a vehicle is not the right thing to do but when it comes to ecu problems there usualy is no better solution and at the least u will have a good known spare . if in fact u have done everything in ur power in trying to find this gremlin and yet to succed that would be next on my list .

mason

Steal one from the boneyard, and try it. They so rarely go bad that the chances of you getting a bad one are, well, low. Probably as high as getting a bad 'new' one.

I have considered both of those scenarios. I can get a new one for a decent price (about $180), but last night I remembered that a friend of mine that owns JeepersDen here in Orlando had two MJ's on his property the last time I was out there so I am going to call him today and see if either of them have one that I can borrow.

Man, $180 is pricey. If you can wait, get the #'s of your ECU and toss a line to Wildman and get one of his.

As a last resort,call me,I'll park mine for a day or two

and ups you my ecu,so you can try it.Mine's a 5 spd.

I have another vehicle to drive,and it's too wet down

here to do any wheeling anyway.

Also,check the cps.One of the bolts came out

of mine wheeling one night,I ended up getting towed

home and it took me 3 days to find it.

It was swingiing on the remaining bolt,doing all sorts

of wierd schizzle.

Did not get to go to River Rock,money's too tight,

but we will get up to meet you two shortly.

Man, $180 is pricey. If you can wait, get the #'s of your ECU and toss a line to Wildman and get one of his.

Tracy...I'll make that a last resort as I have received a couple of options from other folks on here through PM's that may work out. Are you coming up to Ocala on the 25th & 26th for Jeeptoberfest?

If finances allow,absolutely.

First,have to concentrate on keeping

my home.

Yea,I'm in the same biz you are,you know

where I'm coming from.

If you want to borrow it,just yell.

You guys have taken good care of me.

I have a used one on the way that should be here Monday or Tuesday so we'll see what happens. I have also received some other good info via PM from others on here so I hope that I will be able to get it figured out soon. I have to work this Saturday so I will not have a lot of time to mess with it this weekend.

.

.

.

.

WAIT!!!!!!! I know whats not wrong with it.......

Your Jeep Tech did such a good job on your mains that the crank has -310% drag,,,,,,,, sooooooo the crank is actually making itself turn..

I think your engine has found the missing link to perpetual motion!!!!!

or could be a missed vacuum leak... :dunno:

:D

:laughin:

I have had a few people ask if this started after the engine work, but it did not. It has been going on for a while, but it has just become progressively worse. It started out being a 1200-1500 RPM rev, then went to 1800-2000 and hkas now become 3000-3500.

I thought I had it fixed the other day with the IAC change when I drove it and had no trouble at all. Tina took it to work and it went crazy on her. Her commute is about 7-8 miles and it ran at 3000 or higher all the way. She had to shut it off at every stop and had a very hard time keeping it at 25 or 35 MPH in the downtown areas where she has to drive. She had to keep it in 3rd gear and ride the brake constantly just to keep it under control.

Hey,at least she can drive it under those conditions.

Kudos to her,I'm still trying to teach mine to drive

a stickshift.Which is why I haven't swapped out the

BA10 yet,let her wreck that one. :D

ps;

gotta blow outta here,going to meet my first

other mj owner.garmj.Oughta be cool.

Man, $180 is pricey. If you can wait, get the #'s of your ECU and toss a line to Wildman and get one of his.

As I was reading this......I was thinking the same thing, till I came to this :teehee:

Yea, any time anyone want to try a new "used" ECU, drop me a line, I have a bunch of them sitting on the shelf for that reason.

The chance of them going bad?? Slim to none......unless.....they get shorted out either internally or externally.

But.......glad to hear you were able to find one locally ;)

B,

Did you make sure the throttle cable wasn't getting stuck causing the engine to actually run at 3500 RPM?

B,

Did you make sure the throttle cable wasn't getting stuck causing the engine to actually run at 3500 RPM?

I honestly have my doubts that the ECU is the problem, but since I had access to one I figured that this will tell the story for sure. Not real local, but a big thanks to Jake (Akula69) for the help from LA :cheers:

How about something being wrong with the throttle body itself.

Hopefully the ECU fixes the problem but I'm just throwing out ideas (trying to make my $64.99 back)

Anyway goodluck :cheers:

The throttle body itself is simply mechanical so outside of a decent crack in it somewhere, there is not really much that could cause it there.

Keep going though...you never know what thoughts you may inspire :D

Brent , have you had the jeep on a scanner (MT2500 or the similar )? . most of the renix ecu failures I have seen show them selfes as a miss, most of the time the #4 injector won't work because of no signal.

yours sounds like a massive vacume leak. Have you checked the intake gasket? also do you have a "c101" conector ? the c101 if you have it will be above the brake booster . check for bad wires and or conections.

That intake gasket is a weak point, so do as Cabz suggested and check it... Or perhaps even consider just replacing it, kinda an ugly job but you can look at other things when you have it all apart.

I do have the c101 connector and will be working on checking/tracing wires today. I can not see any sign of an intake manifold leak and have tried to check for that by spraying throttle body cleaner all around it while running with no response, so while it still could be possible, it doesn't loook likely.

As long as I keep the IAC unplugged, it runs fine which is still leading me to believe that there is an electrical problem somewhere. I drove it for about 10 miles without the IAC connected and you would never know that it was not hooked up...the truck runs great... :dunno:

I have printed out a bunch of electrical trouble shooting stuff from a .PDF manual that I got and I intend to spend what I need to of today working from that. Electrical stuff is way out of my scope of abilities so this may take quite a while.

The Steelers are on at 8:15 tonight so I better go get to it as that is less than 12 hours from now... :roll: :brows:

I do have the c101 connector and will be working on checking/tracing wires today. I can not see any sign of an intake manifold leak and have tried to check for that by spraying throttle body cleaner all around it while running with no response, so while it still could be possible, it doesn't loook likely.

 

As long as I keep the IAC unplugged, it runs fine which is still leading me to believe that there is an electrical problem somewhere. I drove it for about 10 miles without the IAC connected and you would never know that it was not hooked up...the truck runs great... :dunno:

 

I have printed out a bunch of electrical trouble shooting stuff from a .PDF manual that I got and I intend to spend what I need to of today working from that. Electrical stuff is way out of my scope of abilities so this may take quite a while.

 

The Steelers are on at 8:15 tonight so I better go get to it as that is less than 12 hours from now... :roll: :brows:

Before you tear into it, did you have it on a scanner? what was the tps voltage reading? If not I have an mt2500 scanner with the renix plug . Lemme know :D

Before you tear into it, did you have it on a scanner? what was the tps voltage reading? If not I have an mt2500 scanner with the renix plug . Lemme know :D

I was just thinkn this morning about a problem i had with a ford van a couple years ago that was doing the exact same thing and it was a bad tps (voltage to high ) . i didnt think of as u said u replaced it but Cabz is right check the voltage first either with a scanner or just backprobe it at the tps , the voltage should be between .5v-.8v if it is any higher there is a problem . o and check it with the KOEO and the iac hooked up

Before you tear into it, did you have it on a scanner? what was the tps voltage reading? If not I have an mt2500 scanner with the renix plug . Lemme know :D

I was just thinkn this morning about a problem i had with a ford van a couple years ago that was doing the exact same thing and it was a bad tps (voltage to high ) . i didnt think of as u said u replaced it but Cabz is right check the voltage first either with a scanner or just backprobe it at the tps , the voltage should be between .5v-.8v if it is any higher there is a problem . o and check it with the KOEO and the iac hooked up

when I first got my MJ i had to swap the tps , I tryed every method to adjust it except the scanner and never got it close . the only way to be sure is to set it with a scanner . if it is not set right the whole jeep will act retarded. also sometimes after setting them you have to disconect the battery to reset the ecu or it will still act stupid.

Renix is a funny thing sometimes

if the tps is not between .60 and .70 it won't work worth a hoot