Dme-ECU

[barry]

Does anyone rebuild the above, can they be rebuilt, is it worth rebuilding,
LMK
Thanks
Barry

[mikeedler]

used ones usually sell for about 20-30 dollars

[Rigmaster]

places like Programa sell rebuilt ones, but they're pretty expensive IMHO.

And like Mike said, good used ones are available cheap (though maybe more than $20-30), so it's really not worth trying to rebuild one.

[jlevie]

Used DME's can be a roll of the dice. When we tune a Spec E30 engine we take a half dozen of so used DME's to the dyno (grabbed out of the box at a local salvage yard). The first thing we do is to cycle through those and pick a couple that produce good A/F curves. It isn't unusual to find one or more that don't work well at all (very lean usually). If you have a way to test a used DME (like on a dyno) and know that the rest of the engine management is working properly a used DME will be cheaper than a rebuilt.

[barry]

Thanks Jean,

I bought a few and trying them out, I noticed some white powder in mine it is original when I bought the car new in 1988. I also bought some ground cables from Greg that work real well. Ya I checked out repair, it;s about 200.00, but like you say a good used one is ok with me.
Thanks for your continued interest
Barry

[ECU Doctors]

I am biased of course because we fix ECUs, but jlevie is right.

Used DMEs from ebay and such come from OLD USED cars. These ECUs will develop the same problems that you are having with your own unit right now.

I know that the $20 price tag is attractive, but the uncertainty that your car could stop working in the middle of the road and end up costing you much more in towing fees, repair, diagnostics, etc., is not worth the savings.

[Quinthirty]

I am biased of course because we fix ECUs, but jlevie is right.

Used DMEs from ebay and such come from OLD USED cars. These ECUs will develop the same problems that you are having with your own unit right now.

I know that the $20 price tag is attractive, but the uncertainty that your car could stop working in the middle of the road and end up costing you much more in towing fees, repair, diagnostics, etc., is not worth the savings.

Can you possibly post data or charts of before and after rebuilding an ECU affects performance? Perhaps, you could also enumerate the benefits to generate interest?

[jlevie]

The digital part of the DME doesn't age and either it works or it doesn't. But the analog interfaces to the engine do suffer component aging. The most common problems I've seen is are lean operation. If it only runs lean up to the AFM cutoff point, the input circuits for the AFM are suspect. If it runs lean across the entire operating range the ECT sensor input is suspect. But there can be problems with any of the inputs or outputs. You have to do dyno testing to see how well the DME is working, but that assumes that everything else in the engine and it's management system is working correctly.

[Quinthirty]

Thanks Jim. I'm actually interested to see numbers or charts as I recently had an AFM rebuilt and bought a few DMEs myself. I just wanted to see what to watch out for being a noobie to these things. I'm bent on getting the best performance and efficiency from my M20, or maybe I'm just crazy and delusional. He, he.

I fixed a fuel leak already but couldn't find a shop to do a smoke test where I am, so I'm renting a smoke machine from the entertainment industry to do it myself. Might as well set-up some mirror balls, strobes, and some colored lighting in the garage and have the boom boxes ready. Might as well... All for a vacuum leak test.

I digress...

[jlevie]

Thanks Jim. I'm actually interested to see numbers or charts as I recently had an AFM rebuilt and bought a few DMEs myself. I just wanted to see what to watch out for being a noobie to these things. I'm bent on getting the best performance and efficiency from my M20, or maybe I'm just crazy and delusional. He, he.

If you want the best performance/effeciency, nothing beats time on a dyno. You'll want to do the usual full throttle runs, but you also want to see some part throttle data. Then look at the A/F curves and see how to stoich the engine is.

I fixed a fuel leak already but couldn't find a shop to do a smoke test where I am, so I'm renting a smoke machine from the entertainment industry to do it myself. Might as well set-up some mirror balls, strobes, and some colored lighting in the garage and have the boom boxes ready. Might as well... All for a vacuum leak test.

To properly do a smoke test you need to plug the exhaust and replace the AFM with a plug containing a nipple for smoke injection. The pressurize the intake with smoke to 2-4psi and hold that pressure for 10-15 minutes. Many times I have to do this test more than once as there will be so much leakage the first time that smaller leaks can't be seen. So it becomes test, fix, retest, fix, final proof test.

[Gregs///M]

I can take any DME/ECU apart and re-flow the entire board with new solder. I will also inspect the entire board under magnification and test any "suspect" electrical components. PM me if you are looking to have something like this done.

Check my signature for more info on SI board repair, which can be applied to DME or any other electronic devices such as clusters, etc.

I'm currently in the middle of a cluster re-build, in which I am disassembling an entire cluster and re-flowing with new solder and in-car testing for another member here. I can also perform this for DME.

[barry]

Hey Greg send me your address so I can send you my ECU
Thanks
Barry

[ECU Doctors]

Can you possibly post data or charts of before and after rebuilding an ECU affects performance? Perhaps, you could also enumerate the benefits to generate interest?

Again, Jim's correct. An ECU will work or it won't. It will cause a cylinder misfire, or it won't. It will cause a running rich condition or it won't...

So "performance" benefits/increases after an ECU Repair as in from the stock configuration of the car, that will not happen.

However a rebuilding service of an ECU ensure the reliability and long working lifetime of the unit. (E.G. not ending on the side of the road, and no intermittent issues cause from an old decaying unit, like fuel getting cut off, or sudden loss of spark.)