Techno Duck

Is the DME temp sensor ignored at WOT?

My DME temp sensor tested out fine using the resistance check across the two pins. I repaired the cracked insulation on the wiring also.

Hypothetically, assume the car is at normal operating temp. The DME temp sensor is deffective and still shows the car as not warmed up. If you were to go WOT with the bad sensor, would it still go to open loop fuel maps (preset fuel map) or would it continue to run closed loop using the O2 sensor as reference or perhaps some kind of 'warm up' WOT fuel map?

Still working on my rich on boost issue. The TPS tested fine and the car does seem to go into a WOT map. From zero too full boost it will show low 11's at part throttle, if i go WOT it will drop to an almost consistent 10.8 AFR. I was under the impression the DME temp sensor is ignored when at WOT. If not, perhaps it is an intermittent issue only at load. The sensor will be replaced tomorrow for sake of age (pretty sure its original), but wondering if anyone knew its exact function and effect on DME operation.

fast951

The O2 sensor is used for closed loop, and is ignored at WOT. The Temp sensor is totally different.

For some reason, your car is running rich even at PT. Find out what is causing it (easier said than done), and you car will run at the correct AFRs. 10.8:1AFRs you will see a black smoke behind you!!!

You can use the voltmeter to check the Temp sensor when running, just read the voltage at the back of the DME connector. If you have a PB you can log it...

Assuming your WB is displaying the correct data.Since your car started experiencing the rich AFRs, maybe it's something mechanical.

Take a look underneath the car, if the fuel return line from the FPR to the tank is restricted (bent?), it could raise the fuel pressure causing the rich condition. Even a bad FPR could cause what you are experiencing.

Techno Duck

So the temp sensor does have an effect on DME operation even at WOT? I ordered a sensor through WorldPac and will replace it tomorrow. It tested fine using the resistance checks across the pins (checked on hot and cold engine), but perhaps something is amiss under load.

I have also considered the wideband as just giving me incorrect #'s. I have replaced the sensor and also ran its power source directly off the battery (previously it was run off radio circuit). No effect here. My last check is to ground the wideband controller and gauge directly off the battery. I did check and clean all of its current grounding points with no effect either. So i doubt this is the problem, but will do it anyway to rule the wideband out completely. I also fixed a large exhaust leak between the downpipe and midpipe today (post turbo, pre wideband), i thought it could be skewing the wideband readings, but it also made no change.

I thought about things to check over the last hour and here is what i came up with.

-Pressure test intake from turbo inlet; previously i was doing it from the intercooler inlet. I figure its possible the compressor cover is leaking. I need to goto HomeDepot to see if i can find some PVC pieces to make this work with the couplers i have at home.
-MAF; clean MAF sensor
-Check fuel pressure; the most important thing i need to do right now, i just need to find a gauge that will work on the fuel rail before i leave later in the week, either that or find someone on Long Island willing to loan me a 3-bar regulator.. . I have a new fuel rail incoming that uses an Aeromotive regulator (and includes gauge). Unfortunately i wont be able to install until mid August when i am home again. I figure its possible the 3-bar regulator i have went bad, but i will also inspect the return lines tomorrow.

V2Rocket

could the maf element be heating to the wrong temperature?

pontifex4

Jon, for my edification, where was your insulation cracked? I just cleaned the connectors on mine and it got me closer to running right (on a hot day, the car will finally reach "warmed up" after about five minutes and not spit black smoke out the back when it comes on boost). I'm still having trouble with it on cooler days, or when it hasn't fully warmed up, though, so bought a connector from JoKA and I think I'll take a closer look at the wiring, too. It was doing this even before the MAF install (SciVision, in my case).

Techno Duck

Charlie, it was cracked badly right under the rubber boot for the connector. Honestly i do not think my wires were shorting out as i never had problems with the car coming out of or running in warm up mode when its called for. The wiring also had a tight bend where it comes out of the main wiring sheath (where all the wiring splits off for the oil pressure sender, gauge temp sensor..etc). I cut a slit in the wire sheathing there also so i could inspect the insulation on the wires, but everything was fine.

I have a new DME temp sensor ready to go on, but as usual the weather is no cooperating; waiting for the rain to letup so i can inspect the fuel return line. Also it does not help i have no muffler on the car currently (having new tip welded on).. i did a test run through my neighborhood yesterday afternoon and got alot of dirty looks.. .

Techno Duck

Go figure its always the last damn thing i check! Ten minutes, a flat head screwdriver and a can of CRC MAF cleaner is all it took to fix the problem!

I did check the fuel pressure this morning, i really wanted to see what was happening on boost so i had to do some ghetto rigging. Yes, its taped to my windshield .

Anyhow everything checked out in spec.. my buddy had a can of CRC MAF cleaner on the work bench so i decided to clean the MAF sensor out as a last resort.

All was not wasted effort, i learned a heck of alot about the function of some items on the car, fixed some DME wiring issues and now know everything else is in great shape.. .

JohnKoaWood

FWIW, the temp sensor is used for % correction IIRC, NOT for calling a different map.. it is just correcting (modifying) the map that is there, if your temp sensor is bad, the fault would be consistant regardless of throttle position...