Electrical problem? Need assistance

[tragdor]

I'm not sure what the issue is, but here is the scenario:

I was driving and heard what sounded like a backfire. The check engine light came on and the car had little power for about 5 seconds, but stayed running. The check engine light went off (within 5 seconds). The car drove normally back home and all readings on the dash were within spec. Today I drove the car around to see if anything occurred again. I was coming to a stop and the check engine light came on, the car had little power, and the factory boost gauge was jumping all around, while I was not on the gas. I got home and shut the car off. I turned it on again and the car ran normally for a moment. Then I heard a lot of clicking noises from within the dash/console area, the car idled rough, and the check engine light was back on. The car eventually died. This behavior was the same for several minutes, until I could not start the car anymore. There was a loose negative cable on the battery and I tightened this down. The car then started, but did the same thing again. It's intermitten for sure.

1)Could this be an electrical short?
2)Could this be a problem with my battery cable ends? The negative is pretty beat up.
3)Could this be caused by me not running a ground strap on my exhaust? I haven't been running one, and the issue started not too long (but not immediately) after disconnecting my ground strap.

Any opinions and ideas would be appreciated.

 

[cdm_sd02]

I had something like that in my 91 tsi and it turned out to be the Alt. & Battery. But all my gauges where flipping out, not just boost. The CEL would stay on for a bit, because of the other sensors where flipping too.

 

[DSM8ALL]

Pretty common symptoms of an ECU going out. Look at the stock boost gauge in the dash when it happens. A lot of times it will jump up to the zero mark when the ECU malfunctions. You can also pull the ECU out and see if the caps are leaking or if any of the diodes look burnt.

 

[GooeyGus]

Pretty common symptoms of an ECU going out. Look at the stock boost gauge in the dash when it happens. A lot of times it will jump up to the zero mark when the ECU malfunctions. You can also pull the ECU out and see if the caps are leaking or if any of the diodes look burnt.

Yup. The clicking you hear is the MPI relay, becuse the ECU is freaking out and telling it to shut off/turn on.

This is exactly what happened when my ECU died.

 

[cdm_sd02]

Yup. The clicking you hear is the MPI relay, becuse the ECU is freaking out and telling it to shut off/turn on.

This is exactly what happened when my ECU died.

Yup, that is so true...
I was assuming before the ECU was replaced already, like so many of us have done already. But it's not uncommon for even a rebuild one to die time to time.

 

[tragdor]

Pretty common symptoms of an ECU going out. Look at the stock boost gauge in the dash when it happens. A lot of times it will jump up to the zero mark when the ECU malfunctions. You can also pull the ECU out and see if the caps are leaking or if any of the diodes look burnt.

Is it pretty easy to tell if the ECU caps are leaking or the diodes look burnt? I'm sorry if its a stupid question-I don't have a lot of experience with circuit boards. Thanks to you all for giving me a starting point to begin investigating. I'll try to remove it and post some pictures of what I see.

 

[project98dsm]

I'd start by pulling the ECU and checking your board, mainly around the caps. I have a picture of the ECU from my 91 GSX. I'm in the army and I had to go to the field for a few weeks. I came back and started my car to let it run a bit and it started up fine. I had a 3 day weekend and before work I was going to make a quick run to the store and my car wouldnt start. It turned over and all but did not fire up. After several tests, (spark, fuel, injectors) I found that I was getting spark all across the board but was not getting any fuel past my injectors. The last few times I tried to start my car when I turned the key back to the "off" position the MPI relay started clicking. I pulled my ECU and found this. I have no photoshop or editing programs on my Mac to circle the damaged area but I'm sure it speaks for itself.

Oh yea, and this just happened a couple of weeks ago...so we're both in the same boat. I'm thinking of just getting an eprom and get it chipped from dsmchips. They also include a stock chip that I plan to run until I get my 1g hooked up for the setup that I want. I can go ahead and order the Stage 3 with what I will be running in the future and until then (sadly) just run the stock chip they include. These guys are awesome you should give them a look-see.

dsmchips.com

 

[tragdor]

Thank you project98dsm for posting the pictures. It appears that this may be the problem. I pulled the ECU and it looks like there is some damage around the base of one of the capacitors. Please take a look and give me your opinions.

 

[project98dsm]

Yea it definitely looks like you have some leakage around the bottom cap from the way you're holding it. I'm no expert on boards but even if you don't see any physical damage done to the traces, it doesn't necessarily mean there is no damage done to the board that would cause any erratic behavior. You have several options like I mentioned earlier...you can either send it in and have it cleaned, recapped, and then sent back. You'd be left with a refurbished stock ECU. Or you can have it sent to one of the companies I mentined earlier and they can clean it and have it socketed for ECMlink or a keydiver chip from dsmchips.com. Either option would yield great results. I know Jeff from dsmchips can burn a chip and it be pretty dead on from what I hear based off the setup you're running, which would would probably need very little tuning from an AFC or some other air/fuel controller. But every car is different so it's hit or miss. Your call though

 

[DSM8ALL]

Definately the problem. Not only are the caps leaking, but I can see burnt diodes as well.

 

[project98dsm]

tragdor, do you know of anyone who has an ecu that you can use? I'm not sure of compatibility between year models of 1Gs, but maybe you know someone who has one that you can borrow temporarily until you decide what you wanna do, just to knock off some down time? I'm sure someone in here can offer some insight about swapping out ECUs with earlier 1g models. They should be the same except for the fact that autos have 390cc injectors instead of 450cc, but don't quote me.

 

[DSM8ALL]

All 91-94 AWD 5 speed and FWD 5 speed ECUs will interchange in a 5 speed car, and all 91-94 AWD automatic and FWD automatic ECUs will interchange in an auto car.

 

[tragdor]

Unfortunately I don't know anyone that I could borrow a ECU from. It's alright though, as its not my daily driver. I did want to go either the ECMLink or Keydiver chip option, but I don't have any upgrades that this would benefit and I don't think I can afford to right now, with Christmas and all that. I talked to Steve (wiseman) who will most likely be rebuilding my ecu for me. If I can, I'll get it socketed with a ZIF socket, which would allow me to swap EPROMs once I was ready.

DSM8ALL-
Are the burnt diodes also a repairable option, or would it be better for me to purchase a different ECU?

 

[steve]

Not only are the caps leaking, but I can see burnt diodes as well.

I don't see any burnt diodes. I see electrolyte covering some of the SMD capacitors and what looks like may be a short under C108.

What are you looking at?

If I can, I'll get it socketed with a ZIF socket, which would allow me to swap EPROMs once I was ready.

Unless your changing EPROMS all the time I don't recommend a ZIF socket. They don't work well with V2 DSMLink but should be fine with V3.

 

[tragdor]

The reason that I was thinking about a ZIF socket was because I know at some point I will be going with either a burned chip or ECMLink. Most likely a chip though. I like knowing that all I would need is to have a chip burned, and I could swap it myself, rather than shipping it out to have it soldered in. I was thinking that if I am having it serviced, that I could do the capacitor repair and the ZIF socket done at the same time. Steve, I'll call you regarding this next week for some advice if that is okay.

 

[project98dsm]

Hey Steve correct me if I'm wrong, but wouldn't a 1g auto ECU work in a 1g manual ECU? They are different ECUs, unlike for a 2g since 2Gs use same turbo/injectors for both auto and manual...however wouldn't an auto ECU from a 1g work in a 1g manual, just needs to be leaned out some due to the smaller injector size the auto ECU is tuned for right?

 

[steve]

Getting it socketed is a good idea but there are three type of sockets.

The low end stamped wiper contact sockets are not a good idea in equipment subject to vibration and I won't use them.

A machined pin socket is intended for equipment subject to vibration and is what I use by default. You need to use a flat blade screwdriver or chip puller to remove the chip out of the socket. There is some risk of bending the pins if your ham handed and try to pry the chip out in one shot. These are perfect for someone who changes chips a couple of times a month or less. The offer the highest chip retension with minor effort to install or remove.

The ZIF socket (zero insertion force) opens and closes by a lever. They take no force to install or remove the chip but it requires clearance for the lever to move to operate the socket and clamp down on the pins. You'll find versions of this type of socket on PC motherboards where there are so many pins you wouldn't be able to install or remove a processor without damaging them. I do these as an option for people who are doing code development and changes chips several times in a sitting.

Hey Steve correct me if I'm wrong, but wouldn't a 1g auto ECU work in a 1g manual ECU? They are different ECUs, unlike for a 2g since 2Gs use same turbo/injectors for both auto and manual...however wouldn't an auto ECU from a 1g work in a 1g manual, just needs to be leaned out some due to the smaller injector size the auto ECU is tuned for right?

I've answered that question many times.

The only difference between the ECU is the software. On a EPROM ECU changing the chip would make one into the other. On a non-EPROM ECU there are differences in the idle code because of the load an ATX puts on the engine when in gear in addition to the fuel and timing maps that make me suggest you don't use wrong one to do more than get out of a bind. The injector difference are minor as long as you don't also mix and match the FPR and injectors.

Factory 1G manual 450cc injectors flow about 411cc @ 36.3 psi and the automatics about the rated 390cc with the automatic FPR.

When I make chips for auto cars I use the automatic versions of the software and then make the normal fixes for removing limits and correcting for changes in injectors, MAFs and other parameters like the fuel and timing maps.

People like it that the engine doesn't bog when you put it into gear or slam because it was idling so high in park and neutral.

 

[GooeyGus]

Hey Steve correct me if I'm wrong, but wouldn't a 1g auto ECU work in a 1g manual ECU? They are different ECUs, unlike for a 2g since 2Gs use same turbo/injectors for both auto and manual...however wouldn't an auto ECU from a 1g work in a 1g manual, just needs to be leaned out some due to the smaller injector size the auto ECU is tuned for right?

I have an eeprom ECU that I'm 99% sure has the eeprom of an auto in it, and the car just doesn't feel right. Gas mileage is much less. The car was running fine, but felt like there was a bungee cord attached to the back of it. I recently put in my 5-spd eeprom and it feels much better.

 

[project98dsm]

I have an eeprom ECU that I'm 99% sure has the eeprom of an auto in it, and the car just doesn't feel right. Gas mileage is much less. The car was running fine, but felt like there was a bungee cord attached to the back of it. I recently put in my 5-spd eeprom and it feels much better.

Are you running any tuning software? That sluggishness is probably from the different fuel map on the auto ecu. I had the same feeling in my 2g running rc550s for a while untuned.

 

[GooeyGus]

Are you running any tuning software? That sluggishness is probably from the different fuel map on the auto ecu. I had the same feeling in my 2g running rc550s for a while untuned.

Nope, no tuning yet. If you could tune it out, then I would say that yes they are interchangeable, as long as that is the only difference. Everything else on the car is working fine

 

[project98dsm]

I would imagine that being the only difference. I don't know honestly, I'm sure it could be used as a bandaid just to diagnose an ecu problem...nothing long term though.

So tragdor, good luck bro and keep us updated on the route you take with your ECU.

 

[DSM8ALL]

I don't see any burnt diodes. I see electrolyte covering some of the SMD capacitors and what looks like may be a short under C108.

What are you looking at?





I don"t have photoshop to point out or circle anything in the pictures, but between the upper diode and lower right cap where the cap has leaked, there looks to be a burnt diode. I have had several ECUs repaired, and 9 of 10 have burned or damaged parts other than the caps, caused by the cap leaking onto them. This particular ECU looks to me like it may have some other damaged parts. There are several places that repair/rebuild ECUs as everyone knows.


As for auto and 5 speed ECU differences, in a stock situation, both will run the car, but not optimally. If it is e-prom and is set up to run the correct injectors, then they will all work. I was just trying to let him know what to look for if he needed one to get by.

 

[tragdor]

Issue resolved-the ECU was damaged by leaky caps. I had the caps replaced, ecu board repaired and socketed for EPROM when my upgrades catch up to my hopes and dreams! Thanks to all that assisted! Special thanks goes out to Steve for his work that was completed at a fair and honest rate.

 

[enash99]

Issue resolved-the ECU was damaged by leaky caps. I had the caps replaced, ecu board repaired and socketed for EPROM when my upgrades catch up to my hopes and dreams! Thanks to all that assisted! Special thanks goes out to Steve for his work that was completed at a fair and honest rate.

awesome! grats on the fix. im still working on mine =)