No Start Problem
#196
Pro
Thread Starter
Yes.
Maybe an issue. Some meters are wierd. I see you have it on the 2K range. And the meter is showing 00.2. That "may" mean 0.2 of 2K, I don't know or something like that. If you just hold the two leads together, that is what zero looks like on your meter. You might want to compare notes with someone with another meter and make sure you are reading the meter correctly.
And yes, the bottom line is that you need to read a reasonable resistance value at terminal 13 on the DME plug, which is what the DME brain will see and use as part of its algorithm.
Maybe an issue. Some meters are wierd. I see you have it on the 2K range. And the meter is showing 00.2. That "may" mean 0.2 of 2K, I don't know or something like that. If you just hold the two leads together, that is what zero looks like on your meter. You might want to compare notes with someone with another meter and make sure you are reading the meter correctly.
And yes, the bottom line is that you need to read a reasonable resistance value at terminal 13 on the DME plug, which is what the DME brain will see and use as part of its algorithm.
#197
Pro
Thread Starter
Last edited by Acantor; 05-08-2022 at 02:20 PM.
#199
Pro
Thread Starter
Ooohhhh I see. It is reading 2.76k I believe or 2.76 on the 20k ohms setting. I tested the old one and it reads the same. This makes no sense. If the sensor is good, what other things determine the amount of fuel to the cylinders? @T&T Racing @orig944
#200
Rennlist Member
What orig944 said. Some meters need to be on a range setting that is greater than the expected value. It is always safe to start at a higher range and then work your way down, to get better resolution.
#201
Pro
Thread Starter
#203
Rennlist Member
Congrats on 200 posts to your thread!
Summarize again, completely, the situation where you were able to start the car and have it idle. And then what you do that immediately causes it to not idle.
Btw, please re-confirm that you are getting a tach bounce.
Summarize again, completely, the situation where you were able to start the car and have it idle. And then what you do that immediately causes it to not idle.
Btw, please re-confirm that you are getting a tach bounce.
#204
Burning Brakes
Some hard won knowledge about using your DMM, but now we know your problem is not the temperature sensor. You are back to looking for something else, like an intermittent connection, short, or DME. Know anyone with an oscilloscope that could look at both sides of an injector while you are cranking?
+1 on the tach bounce check. Also the injectors are powered through the fuel pump relay, perhaps jumpering that would rule it out as a possible issue.
+1 on the tach bounce check. Also the injectors are powered through the fuel pump relay, perhaps jumpering that would rule it out as a possible issue.
#205
Pro
Thread Starter
Sometimes, with the sensor plugged in, It would start and hover around 200-350 rpm and kind of chop like a crazy cammed corvette (like someone was giving it a little gas and then almost dying again before it would get another short burst of gas). It would try to clear this up and sometimes it did and took the rpm up to 1200. It then tried to bring the idle back down to regular idle speed but it just died.
In my opinion, another fuel/pulse determining sensor is fighting with the temp. sensor making starting the car "hit or miss" when the temp. sensor is unplugged. When the temp sensor is plugged in, the fuel that it is telling the DME to send to the cylinders is not enough to overcome a false reading from some other fuel injector pulse determining sensor.
Could this be a bad reference sensor. What would I look for for "tach bounce"? since the tach is working, doesn't that mean the sensor is good?
I appreciate the help!
#206
Drifting
I believe the reference sensors are OK because your Tach functions so speed sensor is OK. The reference sensor sets TDC for DME. The engine starts so it is OK
IMO, the issue is in the wiring for the fuel injectors from the DME or an internal component/crack solder connection on DME PCB. There is an initial 5 amp draw to open each fuel injector coil on the 12v supply and hold at about 1-2 amps, but it pulses may, many times. The DME grounds a pair of injectors, so is an initial of 10 amp and then holding at 2-4 amps. So this pulsing can generate heat in the DME causing issues.
So the first cheap thing to do is to unwrap the wires you taped together after fixing the splices and expose the red/blue wire and get it clear so you can get a good photo of its total exposure on both sides of the 9 pin connector. That is the one wire I could not totally see in the photos. Describe how it is spliced/not spliced by making a sketch of the red/blue wire including any connection into the 9 pin plug and then post sketch as a photo.
Then this information should be able to decide the next step.
Do you have access to a duplicate DME? Have you opened the existing DME?
IMO, the issue is in the wiring for the fuel injectors from the DME or an internal component/crack solder connection on DME PCB. There is an initial 5 amp draw to open each fuel injector coil on the 12v supply and hold at about 1-2 amps, but it pulses may, many times. The DME grounds a pair of injectors, so is an initial of 10 amp and then holding at 2-4 amps. So this pulsing can generate heat in the DME causing issues.
So the first cheap thing to do is to unwrap the wires you taped together after fixing the splices and expose the red/blue wire and get it clear so you can get a good photo of its total exposure on both sides of the 9 pin connector. That is the one wire I could not totally see in the photos. Describe how it is spliced/not spliced by making a sketch of the red/blue wire including any connection into the 9 pin plug and then post sketch as a photo.
Then this information should be able to decide the next step.
Do you have access to a duplicate DME? Have you opened the existing DME?
Last edited by T&T Racing; 05-08-2022 at 05:16 PM.
#207
Pro
Thread Starter
OK, I would unwrap the wires you taped together after fixing the splices and expose the red/blue wire and get it clear so you can get a good photo of its total exposure. That is the one wire I could not totally see in the photos. Describe how it is spliced by making a sketch and the post sketch as a photo.
Then this information should be able to decide the next step.
Do you have access to a duplicate DME? Have you opened the existing DME?
Then this information should be able to decide the next step.
Do you have access to a duplicate DME? Have you opened the existing DME?
As for DMEs, I do not have a duplicate and have not opened the existing one.
#208
Rennlist Member
Someone send this man a spare DME unit to try as a test. If I had one, I would. I did have a car once with a bad DME. They are generally rugged but not impossible for it to fail.
#209
Drifting
OK,
I would try to open the connector because there is probably corrosion in male/female contacts for the red/blue wire. I would gently pull the connector apart, do not pull on the wires but wiggle each half of the plug, might need small vise grip type pliers and having a second person release the locking tabs.
I would try to open the connector because there is probably corrosion in male/female contacts for the red/blue wire. I would gently pull the connector apart, do not pull on the wires but wiggle each half of the plug, might need small vise grip type pliers and having a second person release the locking tabs.
#210
Pro
Thread Starter
OK,
I would try to open the connector because there is probably corrosion in male/female contacts for the red/blue wire. I would gently pull the connector apart, do not pull on the wires but wiggle each half of the plug, might need small vise grip type pliers and having a second person release the locking tabs.
I would try to open the connector because there is probably corrosion in male/female contacts for the red/blue wire. I would gently pull the connector apart, do not pull on the wires but wiggle each half of the plug, might need small vise grip type pliers and having a second person release the locking tabs.
I am currently rebuilding my dad's old Fluke 87, so hopefully I will be able to rely on a proven meter moving forward.