6ocyclehum

I'm still trying in vain to figure out my limp mode boost issue (car will boost upon restart, then shortly go into limp 1.2 bar mode).

My master warning light is on,also oil light, the oem pressure sensor has been changed to an autometer one, with a new gauge and it's own wiring.I don't think the original pressure sensor was totally at fault, I'm guessing a wiring issue, because I can connect the original sensor wires with no change in the original gauge reading.

From what I have read about the KLR/DME limp mode, it looks like oil pressure and the master caution light doesn't figure into it. But, my understanding of this system is pretty limited, it would seem common-sense wise, that if the computer saw zero oil pressure or overheating (also sets the master ! light) it would enter into limp mode to save the engine.

So, could this have anything to do with my problem???

Thanks-
Mitch
'86 951

lleroyb

I have never heard of anything besides overboost resulting in the limp home mode. Have you check for any blink codes? See Clarkes Garage site for a how to.

Lou

Van

Mitch, now that I've got my car running well, I experimented with another AFM at the track. Instant problem - causing a full throttle shutdown, then limiting boost to 1.4 bar (not actuating the cycling valve on acceleration).

I put my known good AFM back in, and the problem went away. Again, that is a mis-match of signals from the AFM and TPS that causes the DME to be forced outside of its parameter range.

Have you experimented with another AFM yet?

6ocyclehum

It's not overboosting, it gets code 3-3, which says "replace KLR", been replaced.

I'm just looking at wiring diagrams, not fully understanding all of them, can't tell if the oil pressure sender is somehow relating with the DME, also master warning light......I'm just running out of stuff to check, starting to suspect wiring somewhere...

6ocyclehum

Van- I have not tried another AFM. I tried to do the shop manual test, where you take off the plastic housing to the DME connector plug , plug it in without it, and check the AFM wiring. The connector would not stay seated for me, kept coming partially out of the DME, and I had the ignition on to read the signals, so I got worried I'd fry the DME and quit testing it. I did take the AFM to the bench and applied 9 volts, opened it up and read the readings, it read perfect. Maybe it's the wiring to the DME from KLR? Or the temp sensor in the AFM I've not tested either.

Van

FWIW, my "bad" AFM is a brand new rebuilt one from Paragon Products and it measures up OK on the bench.

But, I can tell you with 100% certainty, it is junk and it is causing my DME to go into overload protection / shut-down mode.

Bri Bro

The computer doesn't set the warning light, it is all done in the instrument cluster by hardware. If any of a handful of warning lights like oil pressure are active, the master warning light goes on. This is done using diodes to make "OR" logic. Basically this means if oil pressure, OR water temp OR... are set, the warning light comes on. The DME doesn't set or monitor the master or any of the other warning lights.

6ocyclehum

Well, that's good to know the master caution doesn't have anything to do with the DME/KLR, so I can rule that out.

On a side note, I removed my gauge cluster yesterday and cleaned all the football connectors, and other contact, retightened the pins on the 3 main electrical connectors, and my gauges work beautifully- full 14 volts, gas gauge reads totally full now upon fill up,and I trust my temp gauge is working correctly also. I replaced some missing bulbs, and I have brake fluid and brake pads warning lights on. I looked at the brake fluid switch, looked OK, and I jumpered the wires together- no change on dash light, left them disconnected, no change in dash light. Must have a short in the wiring, probably is turning them both on.

Still trying to figure out what's up with the oil pressure wiring, I have read that when you jumper the sending unit wires together the gauge reads max, but mine does not.

I'm also running hot, but there is a wealth of info on this in the archives, I'm pretty sure my rad fan switch is not coming on at 92C for the slow speed fans. I have another, hopefully this will fix it.

I have a MBC coming in the mail, as I have grown tired of trying to fix my limp mode......however, I will give it one more shot and try a replacement AFM. Maybe I can find one on ebay for $50 or so.....

Van- that's strange your rebuilt AFM doesn't work correctly. I wonder what the part is that is messed up? When I bench tested mine, I got my readings from inside the unit (used a 9 volt per Clarks Garage), they read perfectly, nice and even throughout the opening of the AFM door, maybe the outputs going to the switch connector don't read the same. Pretty easy to take out, might retest it....

Thanks for input.....