bd0nalds0n

My car is starting to idle richer and richer. I'm going to have to send the LH to Rich to have it repaired, but it's not convenient for me to have any downtime right now. Anyone have a loaner LH I can use for a couple weeks while mine is being rebuilt? Happy to pick up shipping each way, and if there's some other reasonable way I can help out, I will be happy to.

Thanks in advance...

Rich9928p

Brian,

Will you be at Sharktoberfest? I'll be there - perhaps we can work something out so you don't need a loaner.

Lorenfb

"Anyone have a loaner LH I can use for a couple weeks while mine is being rebuilt?"

Since you're located in SoCal and near 928 Int'l, they should be able to provide
you an exchange unit within the same day, thereby eliminating a need for a loaner.
928 Int'l stocks a very complete inventory of parts, e.g. 928 ECUs. Call the guys there,
they can be very helpful in situations like this.

bd0nalds0n

I will be at Sharktoberfest.

I think I'd rather have my board (or whatever) with a new chip replacing the one that commonly fails for whatever Rich charges (which is less)) than a used unit of unknown condition/hours/age.

Rich, that's great news. I'll see you there and look forward to the swap.

Lorenfb

"I think I'd rather have my board (or whatever) with a new chip replacing the one that commonly fails for whatever Rich charges (which is less)) than a used unit of unknown condition/hours/age."

There're many Rennlist sponsors which supply the LH ECMs which have the updated hybrid chip
at competitive prices, e.g. 928 Int'l, and you don't have to wait two weeks.

Note: Besides the hybrid chip update, there're other mods which should be made to
further enhance the LH ECM's reliability. Not all rebuilt units have these additional mods,
which results in another possible failure even though the unit is under warranty.

Tony

Have you considerd a bad MAF yet?
Sounds like that may be a better culprit?

Lorenfb

"Have you considerd a bad MAF yet?
Sounds like that may be a better culprit?"

- Tony -

Best post of the thread!

The LH ECM unit rarely "drifts" to a richer running condition as Tony implies.
ALWAYS have the LH ECM fully tested before wasting money on a rebuilt unit.

Bottom line: Don't get "roped" into having a good LH ECM rebuilt!
They usually just fail because of battery problems, e.g. overvoltage,
and that failure is catastrophic.

heinrich

Hmmm IIRC Brian also has bigger squirters and a bigger heart ....

bd0nalds0n

Here's the symptoms I'm having:

When I do an LH reset by disconnecting the ground strap, everything is great. My AFM hunts like it should at idle and tends to be on the lean side (which is to be expected, I believe).

As I drive the car more and more, especially if I've been getting into boost, eventually upon returning to idle the AFM stops hunting and settles into a modestly rich condition (one amber bar on the Nordskog AFM). Over the last week, it's now settling into the 2nd amber bar on the Nordskog AFM--it seems to be progressively getting worse, as I have had the one-amber-bar-rich-condition-between-LH-resets problem since last December.

After that point, it won't hunt at idle until another reset. When I take off from a stop (e.g., any moderate application of throttle), the AFM hunts like normal, but if I'm settling in at speed (like on a modest downhill slope on the highway), it returns to rich, even though I am on the gas a bit. On an uphill slope at highway speed, it hunts like normal.

My assumption, which admittedly is just that, was that the "drifting" into a rich condition is a (mis)function of the adaptive feature of the LH and not something related to the MAF.

Is there any reason to believe that a ground-strap reset would affect the output of the MAF, thereby affecting the idle mixture? If the MAF gets pegged due to boost, is there any reason it would it not revert back to its normal output without a reset? I have never heard of any of the other supercharged 928s having a MAF problem of this sort...

I don't think it's the 02 sensor, since my AFM gets its feed the output from the stock 02 sensor--so it's not like the 02 sensor is incorrectly undre reporting the mixture as lean.

Maybe John Speake would feel free to chime in here. Loren, if you want to PM me with some more specific ideas, I'd appreciate the input. All I saw on the 928 website last night was $650 for a used LH, so that was my basis for comparison.

I don't want to be an idiotic consumer; however, whether it's $300-ish for a new MAF or $600-ish for an LH, I am happy to pay a premium to have the problem go away without a lot of time/energy spent on diagnostics and downtime, which would cost more from my vantage point--my wife's car is in the body shop, my Speedster doesn't have a top and it's raining in San Diego, and I just want the car to run right immediately.

I still don't think it's the MAF but would be happy to hear theories about why it could be.

Glenferd

Brian, I had similar syptoms on my 88 S4 a few weeks ago. After spending $$ money on a new MAF, I realized that it actually was the LH. I shipped it off to Rich to be rebuilt and now it works like a charm. As a result, I have an extra MAF for sale on Ebay right now.

By the way, dealing with Rich was a pleasure as he provided great service and price.

Lorenfb

"My AFM hunts like it should at idle and tends to be on the lean side (which is to be expected, I believe)."

AFM???? You mean AFR, right?

Boost???? So this is a turbo/supercharged engine now?

"All I saw on the 928 website last night was $650 for a used LH, so that was my basis for comparison."

We all still have phones, don't we? To conduct cost effective business, one calls to
make deals, and one doesn't fully rely on email & the internet.

1. Again, for costly items (LH ECM) one doesn't guess and spend money without
trying another unit to determine if the problem is resolved.

2. Don't assume because someone indicates a resolved problem that your problem
will be resolved by the same course of action, e.g. all pains in lower abdominal area
don't require an appendectomy.

Bottom line: GET A TEST UNIT!
Guard your LH ECM like it's the last one until you know for sure it's bad.

Check here for troubleshooting methodology:
www.systemsc.com/tshoot.htm

John Speake

Hi Brian,
The problem doesn't sound like MAF.

It seems that the fuelling at idle is not really within the range of the O2 loop. If the loop is in control, then you wouldn't have the rich at idle condition. You are just seeing the loop trying to adapt, but it can't.

You probably need to lower the idle fuel pressure, if possible. What size injectors are you running ?

John Speake

Hi Brian,
The problem doesn't sound like MAF.

It seems that the fuelling at idle is not really within the range of the O2 loop. If the loop is in control, then you wouldn't have the rich at idle condition. You are just seeing the loop trying to adapt, but it can't.

You may have an injector that isn't flowing correctly, this may be forcing the loop rich.

What size injectors are you running ?


I don't think it's the LH either, bacause the O2 loop is trying to work.

jyoon

good luck, but i'm not so sure how willing people are to give up there control units without a hefty deposit. i sure wouldn't. just an idea, someone may be more willing to test your unit if you send it to them.

Tony

My second guess will be your throttle switch isnt closing all the way not allow things to go into "idle" mode. I believe your using and 85-86 throttle body correct? with and 87 throttle switch attatched?

Id check that and the cable you use to activate it.
I just did a littlle "C Check" on my system last night and that was one of the things i checked...you should be able to hear it click as the thotlle comes off the bottom stop..then when it returns.

let us know what you find as those with similar set ups may go down the same path at some point.

Looking forward to seeing it and you at the 'fest!