DME question
04-26-2007, 08:06 PM
#1
Instructor
Thread Starter
Join Date: Nov 2003
Location: South Pasadena, CA
Posts: 169
Likes: 0
Received 0 Likes
on
0 Posts
DME question
about 6 weeks ago my car died and wouldn't start. Towed it to a shop and it was a combination of ref. sensors, bad inj wires and output transistors shorted out in dme caused apparently by inj wires. Mechanic got it running. I had them install Vitesse stage II at that time. Got car back, ran great for about a week then died again. later that eve. tow driver was able to start the car and drive onto flatbed. Picked the car up next morning from towcompany. It now will start run for half a second and die.
Towed it back to mechanic. He said he checked dme output and says it's ok. he plugged in a 944 dme and apparently it started up and ran. Now he's telling me it has something to do with the klr output and the dme not picking it up or something because it ran ok with a 944 dme which doesn't use the klr.
This didn't make any sense to me at all. My first thought was the dme is bad and just find a new one. Anyone have any thoughts? The mechanic is pretty smart but I don't think he knows these particular cars very well.
Can anyone here point me to what it most likely is?
Towed it back to mechanic. He said he checked dme output and says it's ok. he plugged in a 944 dme and apparently it started up and ran. Now he's telling me it has something to do with the klr output and the dme not picking it up or something because it ran ok with a 944 dme which doesn't use the klr.
This didn't make any sense to me at all. My first thought was the dme is bad and just find a new one. Anyone have any thoughts? The mechanic is pretty smart but I don't think he knows these particular cars very well.
Can anyone here point me to what it most likely is?
04-26-2007, 10:13 PM
#2
Addict
Rennlist Member
Rennlist
Site Sponsor
Rennlist Member
Rennlist
Site Sponsor
How did he get the 944DME to work with the MAF?
Start with the simple things first:
- Inspect and/or replace the DME relay.
- Check ALL ground connections (By battery, Bellhousing)
- Make sure the MAF is getting +12V on IGN ON. (check between RED & Black wire at MAF connector)
- Determine if you are missing IGN or FUEL or BOTH.
- Use the shorting plug in place of PB (one less variable).
When the KLR fails, you get fuel but no ignition. If that's the case try the followings:
If suspecting the KLR, you can disconnect the KLR, bridge the 2 DME wires:
- DME Signal to KLR (DME #21)
- KLR signal back to DME (DME #32)
NOTE: For testing only. With this setup you will not get knock control and you will not get WOT signal.
If this test does not work, something other than the KLR is the cause.
If the above test works, Remove the bridge between the wires. I would replace the chip in the KLR (any good KLR chip works). I have seen many KLR chips just fail for no reason. If that doesn't do it, try a different KLR.
- If the shop has a scope, he can capture the signals on DME PIN #21 and #31 (#21 OUT of DME, #31 IN to DME from KLR).
If you determine that the DME is the problem, there are a few tests I can email you to help with the issue.
EDIT: If the car starts for half a second then dies it doesn't sound like the KLR is dead. Make sure the MAF is powered and the signal is making it to the DME.
For testing: Set "Min Fuel" to 0.6V in PB. Does the start and run (idle only)?
A long day, will be back tomorrow.
Start with the simple things first:
- Inspect and/or replace the DME relay.
- Check ALL ground connections (By battery, Bellhousing)
- Make sure the MAF is getting +12V on IGN ON. (check between RED & Black wire at MAF connector)
- Determine if you are missing IGN or FUEL or BOTH.
- Use the shorting plug in place of PB (one less variable).
When the KLR fails, you get fuel but no ignition. If that's the case try the followings:
If suspecting the KLR, you can disconnect the KLR, bridge the 2 DME wires:
- DME Signal to KLR (DME #21)
- KLR signal back to DME (DME #32)
NOTE: For testing only. With this setup you will not get knock control and you will not get WOT signal.
If this test does not work, something other than the KLR is the cause.
If the above test works, Remove the bridge between the wires. I would replace the chip in the KLR (any good KLR chip works). I have seen many KLR chips just fail for no reason. If that doesn't do it, try a different KLR.
- If the shop has a scope, he can capture the signals on DME PIN #21 and #31 (#21 OUT of DME, #31 IN to DME from KLR).
If you determine that the DME is the problem, there are a few tests I can email you to help with the issue.
EDIT: If the car starts for half a second then dies it doesn't sound like the KLR is dead. Make sure the MAF is powered and the signal is making it to the DME.
For testing: Set "Min Fuel" to 0.6V in PB. Does the start and run (idle only)?
A long day, will be back tomorrow.