3.2 dying please help

[Mauricio911]

I am at a loss. It seems that this problem is getting worse. Initially I could start the car and after 5 minutes it would die. Then I could restart it a couple times with the same results. Now the car dies in less than a minute and it won’t restart. When it dies it does fairly quickly yet the idle becomes irregular for a couple seconds.

Summary what I have done so far
1) Replaced Fuel filter
2) Put in 44K fuel cleaner
3) Replaced DME Relay
4) Tested continuity on the Cylinder temperature sensor
5) Tested voltage to Volume Air flow sensor (pin 3 had 4.8V which is fine). Also tested for continuity between pin 1 and 4.
6) Charged the battery and the voltage while running is 14

I am not sure where to go next. I could use some suggestions.

[DW SD]

When it dies, immediately check for spark and maybe use the fuel pressure port (driver's side fuel rail) to check fuel pressure.

Maybe your coil is dying and heat opens a bad connection inside?

How are your grounds?
Can you swap the computer with a known good one? Maybe it gets hot and a connection opens up.

If the fuel presure is low (when it dies), it would sound like your pump is dying.

Doug

[porschenut]

I would say fuel pump.

[donnieknoxville]

Have you wached the temp head sensor's electrical output when the car died. Mine failed intermittently, drove the mechanics nuts. After several trips to the wrench, they finally watched the sensor die on the dyno. $40 later, I was good to go.

I have a 1987 Carrera Cab.

[bigrubberjeep]

Mauricio - I was having the same problem, my wrench said it was the "DME" and he "fixed it" however I think there is still another issue because it now runs a bit rough. A few guys I did a run with this weekend said to have my injectors tested and rebuilt, these were suggestions from people that had the same issues as you and me.

[don911]

I had a similar problem. Car would not idle or it would cycle through rpms bouncing from 500-1300 and eventually die.

My issue turned out to be the connector that goes into the air flow meter. There are 4 contact in that connector and two of them were being pushed out when the connector was installed. There's a boot on the connector so it's not obvious that all 4 contacts were not making good connection. You can easily check by pulling the boot back and check that the contacts are all seated in the connector.

The lack of good connection was causing a bad a/f mixture. Can't remember if it was really lean or rich.

If it's not the a/f mixture, I'd guess fuel pump or fuel pressure.

[ZOA NOM]

Start with your DME relay under the driver's seat. This is a high failure item, and easily replaced.

edit: DUH, just read your list. Sorry. However, it is not uncommon for you to receive a bad relay. Also, you may have a problem with one of the flywheel sensors (TDC or Speed). Check these at the three connectorson the bracket behind the heater blower motor.

[Mauricio911]

This is my next plan:

1) I will get a fuel pressure gauge to check the pressure.
Are the threads standard on this? Is this something any Pepboys will have?
if the pressure is low then I will replace the fuel pump.
The fuel pump was replaced about 30-40K miles ago though. I was thinking that since the pump was not loud I was good to go.

2) Check the coil
3) double check that the Volume Air flow sensor pins are making contact (this is the 4 pin connector that goes to the air flow meter)

4) I am not sure how to check the temp head sensor's electrical output when the car dies. Do I do it while the car is running or right after it dies? I don't see in the Bentley manual what the voltage should be. The resistance was fine when I tested it

5) I will check injectors. I would think this would make the car run rough but not die. Additionally I would have thought that the 44K fuel cleaner would have made a difference on this

6) No access to a working DME or that pin out test harness used to test it. Hence if it comes to this I guess I will have to take it to my wrench

ZOANAS, you bring up a really good point about the DME relay. When I replaced the DME relay the car did run fine for about a day or two. I actually thought I had fixed the problem.

Is it possible that the DME relay can go bad in a day or two?

[ZOA NOM]

Sure can. They can have stress cracks in the solder joints that flex and worsen after mounting. They can also be frustratingly intermittent.

[syncroid]

Before you go and spend a bunch of money, pull your speed and reference mark sensors out. Make sure they are clean and the cables are not deteriorated. Re-install them and make sure that you have a .80mm air gap for them. I have seen this cause the problems you are describing.

[ZOA NOM]

You can't just "pull" those out. The motor needs to be dropped to get to them. You can check them at the connectors behind the blower.

[syncroid]

You CAN just pull those out! I do it frequently.

[bigrubberjeep]

Originally posted by syncroid
You CAN just pull those out! I do it frequently.

Please explain how

[jbell959]

Check the Head Temp Sensor... I had a similar problem.

[syncroid]

Remove the driver's side rear wheel. Remove the two bolts holding the sensor bracket. You may have to remove a third bolt in the sheet metal holding the speed and reference sensor harness. Once this is done, swing the speed/ reference sensors with bracket out. Look on the end of the speed and reference sensors to make sure there is not expcessive clutch dust or other magnetic debris on them. The sensors are held into the bracket with 5mm allen bolts. You will need to remove one of the sensors from the bracket. Get a small piece of .80mm feeler guage and glue it onto the sensor. Reinstall the bracket (loose) Install the sensor that you have the feeler gauge glued to. You want to do it on the sensor that counts the teeth on the flywheel. (not the pegs on the flywheel) Push the bracket assembly gently but firmly enough against those teeth and secure the bracket bolts. Next, remove the sensor and peel off the feeler gauge. Re-install the sensor and your measurement is done.
It is easier said then done, so take your time.

[rick-l]

Originally posted by Mauricio911

3) double check that the Volume Air flow sensor pins are making contact (this is the 4 pin connector that goes to the air flow meter)

If you go to this site and go to air flow meter there is a much better test.
http://frwilk.com/944dme/

p.s. not sure how well this site is working. hold your mouse over the tabs to find air flow meter.

[greglepore]

CHT. Continuity doesn't tell you much, and sounds like it fails as it warms up.

[PatrickB]

With the symptoms noted in the first post, My vote is for the CHT as well... You are rarely ever going to catch that sensor in failure with an ohm meter...
If it hasn't been change recently, it will fail on you in the future anyway... Just replace it... It eliminates one more piece of the puzzle.

[Lorenfb]

The problem you describe is typically the temp sensor. When it fails, it fails in
the open state causing a full rich condition. A simple solution to isolate & eliminate
the temp sensor is to use a paper clip to jumper the temp input to the DME ECM.
This is done by removing the upper connector (of the three on the left side of the
engine) and inserting the paper clip. The engine will run fine but may be a little
difficult to start when cold and not accel well.

Bottom line: Always carry a paper clip and a DME relay in the glove box.

[Mauricio911]

Thanks everyone.

Loren, I tried the paper clip on the cyllinder head temperature (CHT) connector. The car started and died 10 seconds later. Does that rule out the CHT?

Then I decided to try my old DME relay. The car still would not start (paper clip was out). Yet after a few trys and tapping on the old DME relay the car started. I let it warm up for about 20 minutes. Which is the longest it has run in a while.

Obviosly, I though that the new DME relay was bad. So I plugged in the new DME relay and the car still starts and idles fine!!

I also checked my records. The CHT and Fuel pump were replaced about 30 K miles ago. I found no record of ever changing the DME relay since I owned the car (50K miles ago) the car has about 120K miles now.

Also I did noticed that idle is a bit higher than usual. It is around 1,100 to 1,200. I don't know if that means anything.

Also checked the voltage on the battery while the car was running and it is a 14.2 which rules out alternator issues.


I am not sure what to think. Perhaps I should try installing a 3rd DME relay to see if that fixes the problem. Thoughts?