ECMlink Going lean when letting off throttle

[noitsalaser]

I just got my 90 Laser RS back from the shop where I had a new clutch, CAS/ pigtail, coolant temp sensor/pigtail, used transmission and some seals, ect installed.

Drove home and have a CEL. Hooked up to log and see that I'm going lean (21.4) when I let off the throttle to shift. Is this a tune issue or BOV issue?

Had a really bad boost leak when I took it in. Also don't yet have a wideband. Just using the estimated values showing while logging. I believe I had a detonation on my way home.

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[pauleyman]

Ecu pulls fuel when throttle is closed fully and rpm is above 1500. What is the CEL?

 

[noitsalaser]

Ecu pulls fuel when throttle is closed fully and rpm is above 1500. What is the CEL?

O2 sensor signal
I cleared it and drove before the log. It hasn't returned as of now

 

[AWD-Tony]

AfrEst is calculated by the ECU from airflow and fuel delivery. It’s not for tuning your AFR’s but should be inline with where it should be.

You’ll see once you install a WB that AFR’s go full lean when you’re off the gas. Fuel is completely shut off when idle switch is activated above 1500 RPM’s. You can also verify this by looking at your injduty

 

[noitsalaser]

*update*
Took the car out today and was cutting out on me while driving. The tach and dash boost gauge dropped in and out. No response. Like the car was off but not. Got it to the shop that just did all the work and we swapped my ecu for a factory eprom unit I got with the car and so far so good. Could it be a bad install on the link chip?

 

[AWD-Tony]

Hard to say. Sounds like it lost battery power/ground.

 

[steve]

Could it be a bad install on the link chip?

Maybe, who did the work. If it was ECMTuning it's not that likely but even the best have problems once and awhile. If it was someplace else the odds go up quickly.

 

[noitsalaser]

Hard to say. Sounds like it lost battery power/ground.

That's what I was thinking but all of my engine harness was checked at the shop. Since I swapped the ecu it hasn't happened and no CEL. I'm just having a problem keeping idle above 500rpm and gas mileage is terrible.

Maybe, who did the work. If it was ECMTuning it's not that likely but even the best have problems once and awhile. If it was someplace else the odds go up quickly.

I'm not sure who did the install. I doubt it was professional. I opened the box and the board has something on it and finger prints. I had to get the light just right to see it. Probably gonna send it in or find another one so I can at least log.

 

[AWD-Tony]

Not a bad idea if something looks off. The car looks stock in your profile except a boost controller. Does the tune look stock and can you post a log?

 

[noitsalaser]

Not a bad idea if something looks off. The car looks stock in your profile except a boost controller. Does the tune look stock and can you post a log?

Very stock. Supposedly built bottom. Didn't look like anything but a refresh when I had the oil pan off. Does have ARP head studs. 14b turbo and (a) profile cams. Cams were spec'd when the valve cover was off. Only parts on the entire car that aren't stock is MBC, boost gauge, mechanical oil pressure gauge, magnaflow muffler and Megan coil springs

 

[AWD-Tony]

Yeah. I doubt it’s a built motor and most likely just rebuilt if that. Again, if the tune looks stock, send it off to ecmtuning.

 

[noitsalaser]

Yeah. I doubt it’s a built motor and most likely just rebuilt if that. Again, if the tune looks stock, send it off to ecmtuning.

It's definitely rebuilt with the balance shaft delete. 40,000 miles before I got it. The tune on the unit with link runs the car great besides the random cut out. The board is dirty with some unknown substance that can barely can be seen. The tune on it is stock with EGR and knock sensor shut off. I took out that ECM and put in a stock eprom 90 ECM and it runs good without the cut out issue. The stock unit has a hard time keeping the idle up above 500 on startup. It's really bad on warm starts

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is it worth saving this or should I send in the clean stock one to have link installed

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[Imback]

Just post a Log so many variables.

 

[noitsalaser]

Just post a Log so many variables.

How do I upload a log? I can't seem to figure it out or find any information on how to

 

[steve]

The same way you upload a picture, click on add Photos and select the DSMLink elg file instead of a jpg or png file.

I took out that ECM and put in a stock eprom 90 ECM and it runs good without the cut out issue. The stock unit has a hard time keeping the idle up above 500 on startup. It's really bad on warm starts

That's a converted non-EPROM ECU. I don't see anything in the pictures that would be an problem off hand. How about a picture of the whole thing so I can see the numbers on the white connector and everything else.

The issues with the stock ECU may be due to problems with that ECU or the wires for pin 6 and 14 were swapped to use a 91+ ECU. When you have time let me see good pictures of it too.

 

[We're on Boost]

The board is dirty with some unknown substance that can barely can be seen.

The "unknown substance that can barely can be seen" is probably the conformal coating. That's a pretty good description.
I don't know much about it. And I don't know about the "dirty" part.
Anyway it's some type of plastic stuff. Steve would know what it is and why it's there. Or you could google "circuit board conformal coating".

 

[steve]

Steve would know what it is and why it's there. Or you could google "circuit board conformal coating".

I think it's wax based. The boards are dipped into it while it's molten and the extra drips off as the boards move on the production line.

It's there to protect the parts and connections from moisture causing corrosion. But it also allows the electrolyte from a leaking capacitor to wick between the coating and the board eating the metals as it spreads.

I used a spray based conformal coating to replace the factory coating that had to be removed when repairing the ECU's. You can tell it was there because it's glossy where the factory isn't.

AfrEst is calculated by the ECU from airflow and fuel delivery. It’s not for tuning your AFR’s but should be inline with where it should be.

I always thought of AFREst as the Target AFR the ECU was shooting for based on airflow, engine load, and fuel map. If you have a WB O2 Sensor (Actual AFR) and it doesn't match AFREst, something is wrong.

In closed loop operation the ECU uses the NB O2 to correct for "something being wrong" via the fuel trims. In open loop there isn't any feedback so at best the AFR the ECU wants is an estimate of what it's going to get.

 

[We're on Boost]

It's there to protect the parts and connections from moisture causing corrosion. But it also allows the electrolyte from a leaking capacitor to wick between the coating and the board eating the metals as it spreads.

I used a spray based conformal coating to replace the factory coating that had to be removed when repairing the ECU's. You can tell it was there because it's glossy where the factory isn't.

Oh I get it now finally after all these years, why the conformal coating doesn't shield the board from leaked electrolyte. I always thought the leak would be on top of the coating and the board is underneath the coating, thereby protected. But since the capacitors are under the coating too, the leak is already under the coating when it happens! Bummer.