mj1pate

It started in late June. My 86.5 automatic began stalling out, after driving between 10 and 60 minutes. It would turn over willingly, but fail to start until it was almost stone cold. I replaced the crank position sensor and fixed all vacuum leaks (but at the vacuum modulator) and it ran regularly and reliably for 3 months.

I recently discovered that the hard shifting was caused by a vacuum leak to the modulator. I serviced the transmission and ran a new vacuum line. I also checked the crank end play (.27mm). The transmission shifts marvelously now, but I immediately, subsequently noticed an erratic idle on startup. During my next commute to work, it died on a busy, sloping, freeway entrance ramp during rush hour. It cranked willingly but refused to start, until the wrecker driver dropped me off 1.5 hours later.

I will do all the static resistance checks, but need a method of gathering data on the road when this happens. Short of spending hundreds on a mobile diagnostics system, what methods have Rennlisters used to determine the presence of spark, fuel pressure, and injector pulsing when there is just yourself at the scene?

Mike

JHowell37

For the early 32 valve engines the LH diagnostic manual is very thorough and helpful.

mj1pate

correct...and I have those and should be able to resolve any idling issues in my driveway and there is the need to collect much data. When everything checks out and I head out for a test drive around the village, I'll want to take along a pair of sneakers, a windbreaker, a bottle of water and ??? diagnostic equipment.

For example, if spark and injection are being totally shutdown during driving, then perhaps the alarm system is kicking in unsolicited. Collecting data at the time of the breakdown is invaluable. But, its a challenge to gather spark and fuel system data when there is only yourself and the car
on the side of the road. I can think of a possible data collection system, but am looking to see what others have done.

Mike

mj1pate

On that train of thought....have others experienced alarm shutdown while driving? I'm wondering if a simple use of the long key would have put me back on the road....

Mike

mj1pate

On a piece of Allen's advise from a previous thread, I checked the computer power connections at the battery and they were loose as can be. Maybe problem solved, but certainly one fewer gremlin.

Mike

mj1pate

BTW: failing to check this prior was residual of the excellent cranking that I was getting...from a different battery connection, as it turns out. Kind of insidious...

Mike

123quattro

One good check is to use a can of starting fluid. If it starts and then dies, you know you are missing fuel but have ignition: possible faulty fuel pump. If it doesn't, you probably don't have fuel or ignition: ecu is not working correctly. You could also carry a timing light with you. Once the engine dies, go hook it up to any plug and watch it while you crank. No flash, no ignition.

mj1pate

right....this is the measure that I had taken...I'm also mounting a fuel pressure gauge on the fuel rail. Problem is that you can't use these tools if its just you out on the road, and the car won't start. In other words you can't be turning the ignition key and watching the instrumentation under the hood.

I'm thinking of replacing the analog fuel gauge with an electronic unit mounted in the cabin. In addition, I might rig an inductive pickup to #1 plug wire and connected to a microprocessor that also receives input from the test TDC pickup ( the second crank position sensor). A little micro could determine if #1 is firing in approximately the right time. All that is missing is a injector fire pickup. Anyway, these bits of information gathered on the road side could help point at where to start investigating once the car has been towed back home. This may be moot for the moment, because my computers' bus connection at the battery was just hanging on the battery terminal stud. That's been fixed and the car sounds very happy at the moment. But I think about these things every time I'm waiting the hour for the tow truck to arrive.


Mike

123quattro

The cord on my timing light is long enough that I can hook it up and lay it at the base of the windshield. Crank the car and point the light at you with your hand out the window. It won't tell you where the timing is, but it will tell you if the ignition is working.

SteveG

It's been awhile since I saw this topic but searching under hot no start will surely bring up info.

Lizard928

if you have an anolog fuel pressure guage it will tell you if fuel is your issue.
look at the guage after cranking for abit it is at 40PSI if it is then you have proper pressure, if it is at zero then fueling is your issue.