BLM pegged at 160

[AT7WE2]

looking for some suggestions as to what might be the problem with my GN.
the car sat in the garage for several months while I saved up for a tranny rebuild. It ran great before the downtime. I just got the car back up and running but now it's running very lean - or at least that's what my Scanmaster indicates. I just took it for a test drive and here's what I recorded off the Scanmaster:

idle, after warmup, before driving, trans in park
O2 mV: bouncing all over between 113 - 789
O2 cc: slowly cycling from 0-255
TPS: 0.38
AF: 04
INT: fluctuating 134-150
BLM: steady 160
LV8: fluctuating 26-29
IAC: 38
CLT: 153
ATS: 60
rpm: fluctuating 825-875

idle, after warmup, before driving, trans in drive
O2 mV: bouncing all over between 093 - 783
O2 cc: slowly cycling from 0-255
TPS: 0.38
AF: 05
INT: fluctuating 137-148
BLM: steady 160
LV8: fluctuating 33-34
IAC: 51-54
CLT: 157
ATS: 67
rpm: fluctuating 775-825

after WOT run, idle, trans in park
O2 mV: bouncing all over between 070-781
O2 cc: slowly cycling from 0-255
TPS: 0.38
AF: 04
INT: fluctuating 139-150
BLM: steady 160
LV8: fluctuating 24-27
IAC: 30-31
CLT: 162
ATS: 68
rpm: fluctuating 850

WOT hold values
O2 mV: 023
KR: 20.2 (yes, I *eventually* got my foot out of it!)
MAF: 205 (this was the highest value I saw out of several WOT blasts. I don't know if it would have kept climbing since I kept running out of room)

basic vehicle specs:
'87 GN
stock injectors
stock MAF
stock turbo/IC
Walbro 307 hotwired
adj. fpr set at 45 static
boost peaking at 16 psi
did I miss anything?

I've checked grounds, vacuum lines, tap test on the maf, changed O2 sensors. None of that made any difference. Don't know what else to check. Any help is greatly appreciated.

Thanks,
Rob

[Mistascott]

Welcome to my world. Read Razor's section in the Library, it gives a great diagnostic review of the likely causes and how to find them. Mine is currently pegged at 150 at idle.

p.s. Your TPS is low, should be .42-.44 at idle.
Your closed loop idle counts should be between 20-40.

20 DEGREES OF KNOCK :SHOCKED: :fragez:

That is very bad, you will blow your headgaskets in no time. Have you tested or just listened to the vac lines? Try Razor's technique of blocking off the vacuum block with gasket material and see if the BLMs go down. Then check IAC seal and fuel pressure as the next culprits.

[TurboJim]

AF: 04
INT: fluctuating 134-150
BLM: steady 160

MAF of 4gps is too low. Try cleaning the hot wire in the maf, it could have crud on it. If the sensor is misinforming airflo, oin the low side, fuel will be lean. The O2 will show it and the ecm will attempt to adjust it.

Generally you'll see 5-6gps at warm idle. And yes, at idle 1 gps is a LOT.

Additionally, I'd look for a possible post MAF air leak. If you have a pass side breather, the rubber plug that covers where the pipe USED to go on the inlet bell, the inlet bell gaskey, the flex hose between the AF and the turbo, etc.

Thats about all I see that I dont like.
Jim

[AT7WE2]

Thanks for replying guys. I've read Razor's post and I've checked most of what he mentions. At this point, I feel pretty confident it's either the FP regulator or the MAF sensor and from your comments, it sounds like it's much more likely to be the MAF sensor. Is it common for the MAF sensor to fail or malfunction is this manner? I thought they just went belly-up all at once and quit working completely.

Thanks,
Rob

[TurboJim]

Thanks for replying guys. I've read Razor's post and I've checked most of what he mentions. At this point, I feel pretty confident it's either the FP regulator or the MAF sensor and from your comments, it sounds like it's much more likely to be the MAF sensor. Is it common for the MAF sensor to fail or malfunction is this manner? I thought they just went belly-up all at once and quit working completely.

Thanks,
Rob
I would verify no unmetered air is entering the engine, or the hot wire isnt simply dirty before throwing parts on it, but hey, its your wallet

[AT7WE2]

Jim,
good point. :top: I'll check the hot wire in the MAF. any suggestions on what to clean it with? I figured aerosol brake cleaner, no? As for post MAF air leaks, I've done a visual inspection as well as a tug-pull-twist check on all the vacuum lines with the engine running and didn't notice anything at all. While I've got the brake cleaner out, I'll do a vacuum leak check with it. Thanks again for your input.

Rob

[Chuck]

Do not use brake cleaner on the MAF. Carefully remove the screen[s], and use spray electronic cleaner. When you get the cleaner, BE SURE it states it's safe for plastics!!
Do not use air to blow it out.....

When U R done, be sure the MAF is not put back on the car backwards..... :yessir:

[AT7WE2]

Thanks Chuck, I'll pick up some electronics cleaner on the way home today. Now that I think about it, the brake cleaner is probably a little too agressive for checking for vacuum leaks also.

I'm planning to tinker on this tonight so I'll post up the results.

thanks again.

Rob