So I finished putting the car back together and it runs great... but I think only bank 5-8 is running (so not great). When the key is turned to the on position, the CEL for 5-8 comes on, but 1-4 does not. I didn't think anything of it because the light was coming on prior, so I figured it was a burned out bulb. When I put the motor back in after the major, the main ground to the transmission wasn't installed and the car wouldn't start. At that point though, both CELs would come on prior to startup. I found the ground hidden away, and hooked it up and the car fired right up. I drove it around and it was a turd but was very smooth. I put my hand near the headers on 5-8 and they were very hot. I could touch the 1-4 headers though. Just in case, I pulled the cluster and swapped the 1-4 CEL bulb with a seat belt bulb that I know works because it's annoying... The CEL bulb was good as the seat belt light still comes on. I let the battery sit disconnected overnight and that didn't help either. I also, pulled the ground back off and it did nothing. Then, I installed new crank sensors and nothing changed. I then swapped ECUs from side to side and things got interesting. With the ECUs swapped, neither CEL lit up and the car wouldn't start. I swapped them back and the 5-8 CEL came on again. So I'm not sure if that means a bad ECU or not because with them swapped, nothing happens. Swapped the injector relays in the foot well and nothing. Also, disconnected the CAT ECU on the 1-4 side and that did nothing. Basically, I tried everything I could find using the Search function. I'm going to play in the fuse box this morning and see if there's anything funny going on in there. Any thoughts? My brain is fried on this one and my wife is tired of me in the garage.
I just replaced the ground strap from the battery to the frame and to the transmission because I've read those can be the cause of a lot of things. And, no help. I also pulled the #1 spark plug and it's never been fired.
There is a grounding cable from the gearbox to the battery as well. Check all of your grounds, then double check your major connectors (injection harness, coil pack, etc.) for bent pins. I couldn't tell from your description, did you swap ECU's? If not, try that as well.
if you swapped ecus and the other bank didn't run then I think you may have a combination of problems. Swapping ecus should have allowed the bank that WAS running to continue to run fine if the ECU was good, but since it didn't, that would meant that ecu is bad. However, the 4-8 bank didn't run either when the "good" ecu was swapped to that side, which means something else is also keeping it from starting up. So I think you may have a bad harness or a short somewhere in that harness which possibly fried that side's ecu. Time to get a wiring diagram and do some continuity/resistance checks.
I was thinking along those lines, but the 1-4 CEL was working before I connected the ground to the transmission. So that means that when I connected the ground, it somehow fried the 1-4 ECU. However, I swapped the ECUs back and the original 5-8 is still working, so it wasn't fried when on the 1-4 side.
Probably because the circuit that fried the ecu now has a fried connection and is no longer forcing voltage to that ecu
Sorry I read your description again and realized plain as day that you swapped your ecus. Don't know how I missed that. But I'm pretty sure you have a fried ecu and a short circuit/burnt wire somewhere in the harness
One known damage to Motronic ECU-s is by a bad Idle Control Valve. It blows a couple of transistors inside the ECU causing bad idle which is not cured by a new ICV. This damage can sometimes disable the whole ECU. Perhaps swapping the ECU-s together with the ICV-s is another test that could be done. Image Unavailable, Please Login
I'll check the ICVs today or tomorrow. I'm thinking about sending my ECU to ECU Doctors and seeing what they say. I would imagine they could tell me exactly what part of the ECU is toast and it could help lead back to the cause. If they can't tell me the cause, I'll be spending quite a bit of time troubleshooting with a meter and buying another ECU anyway. I've seen one reference to ECU Dotors (US, not UK) in searching, has anyone ever heard of them?
Before you do that.......... Try checking the white connector next to the Motronic ECUs. That is what sends the signal to the the dash. You can see a picture of it in post #4, in the link I have below, (the chip removal link). 1) The old EPROMs degrade and can start causing issues. I was having weird issues for a while an putting in a fresh set of "chips" helped clear up a bunch of erroneous running issues. This thread shows how I did it. http://www.ferrarichat.com/forum/technical-q-sponsored-algar-ferrari/351819-348-ecu-removal-chip-removal.html 2) The female junior timer pins, in the T55 connector, wear out and lose their ability to apply the proper amount of force needed to make good contact. Here is how I repinned my connectors. http://www.ferrarichat.com/forum/technical-q-sponsored-algar-ferrari/444155-348-motronic-2-7-connector-harness-repin.html
Any updates? Not starting correctly after a major is the worst. All that time and money without the satisfaction of a good start. Hopefully everyone here can help you out!
I haven't had a chance to yet. Maybe tomorrow night a little bit. I'm going to play with all the connectors when I get a chance, starting with the white one ernie mentioned. I'm going to go through ECU the connector using this information: https://www.ferrarichat.com/forum/348-355-sponsored-bradan/444999-348-motronic-2-7-diagnostics-motherlode.html
I stepped through the 2.7 diagnostic yesterday and everything that I could test came back generally correct. There were a few readings where the resistance was higher than listed on the sheet, so I checked it against the 5-8 bank and the readings were exactly the same. The ECU will be at ECU doctors today or Monday and hopefully they can tell me what caused the problem.
I followed the workshop manual instructions for as much as I could without being able to run the engine. It all seems to check out ok so far.
So my 3 month old was sleeping and my 2 year old was running around with my father and I had a few minutes to play around with the car. I thought since everything I could check on the ECU harness seemed to work, that I'd swap the ECUs and then start swapping relays to see if I could get the 1-4 bank to show a CEL and maybe even start. I swapped the 5-8 ECU to 1-4, turned the key to on and the 1-4 CEL lit up. I cranked it, and it started. I have no idea what I did that fixed it besides pulling and reinserting all relays and fuses in the step pad and replacing the ground straps from the battery to the frame and the frame to the gearbox. The ECU shipping tracking is showing that it'll arrive at the ECU Doctors on Monday and then I have no idea how many days that will take IF they can actually fix it. Maybe I'll have the car driving in the next week or so on all cylinders. I will be adding a or the Connector Kit to the list of things to do now though just in case.
I figured that's what happened, but it just doesn't make too much sense to me. When I swapped the ECUs side to side the first time, nothing worked at all. Now 1-4 works with the 5-8 ECU. I'm not complaining , just wondering if it'll happen again... well waiting if I'm honest with myself.
Cars that are driven occasionally only do suffer from bad contacts in connectors due to moisture ingress and corrosion, especially when they are 20+ years old. The lower the mileage, the more chance of having corroded contacts. It is also not recommended to high pressure wash engines of modern cars (i.e. cars with many Bosch connectors) as the water can be pushed into connectors and stay there for a long time causing corrosion.
Well it does only have 20500 miles and only 1500 miles over the last 11 years or so. I knew going in that it needed a lot of TLC.
I received the ECU back today from ECU Doctors. I plugged it in, reconnected the battery, and it fired right up. There were a few burned up diodes and the memory chip had issues. They installed a new stock tuned chip and sent me a second chip for the good ECU in case there was an aftermarket chip in it. For $475, I'm pretty happy with their services. They were quick and communicated through every part of the process. I figured it would fire right up because I can't drive the car right now because of rain and with a stupid hurricane coming, it looks like I won't get to drive it for at least a week.
