Hot start problem

[thekidd]

I have changed the Speed/ reference sensors, DME and AFM, Battery, alternater, DME relay, FPR and Damper. I have had some trouble gettting her to start, then get her running for a while (30 mins), and now I am having trouble getting her to start after she has been running for some time. Yesterday I let her run for a while, then she shut off out of nowhere. Didnt start right away, but about 2 hours later she started right up, and I shut her off. Today, I was playing with the 2 relays (fan and DME- both the same) and the Clarks DME "Y" jumper. I elimianted 1 of them- the one that wouldnt start the car when she was cold. I got the new DME relay, but she didnt start while she was still warm, above the 1/4 mark. 2 hours later, I started her and she ran for about 10-15 mins., shut her off, and she didnt re-start. Waited for another 2-3 hours, and she started right up. When the tach bounces, she will start right away, 90% of the time, other 10% takes 20 seconds about- happened twice. Other times when she doesnt start, I notic that the tach doesnt bounce.

[thekidd]

No spark when engine is hot/ warm (neddle is in middle of first box) Ignition coil or switch? But will this happen when the engine is hot? Will start when I let her cool all the way. Will start everytime in the morning, or after I havent started for a while 5-6 hrs. Wont try starting her after a long time because I know she probally wont start.
Tried to wiggle the reference sensor when brother was trying to start the car.
When I replaced the FPR and Damper, I was getting fuel due to having fuel from the end nut at the rail, not much (with engine cooled, damper doing it job, correct?)

[Razorback1980]

Get it in a no fire state and then do these tests:

With the key on check for voltage at the coil and at one of the injector plugs.

No voltage at the coil means the ignition switch is suspect/bad. Could be the connector at the back of the ignition switch too.

No voltage at the injector plug (pull one to check) but at the coil means the DME relay is suspect/bad.

Voltage at both means the reference sensor is suspect. Check the sensor connectors. Could also be an out of adjustment sensor.

No spark can also be the HV wire from the coil to the dist cap. Can also be a broken or loose rotor. The ignition switch could be making the circuit to the coil when in the on possition but not in the start posstion. Use a test light with aligator clips on the power side of the coil to see that voltage is there during cranking.

You can bypass the DME/fuel pump relay with a simple "Y" wire jumping 87, 80 and 30 together. Put the 30 plug in last.

In most no start cases it's not the coil or the wires or the dist cap or the rotor. Usually the DME relay, ignition switch, reference sensor(s), broken timing belt then fuel pump. The DME is way down the list.

[Slam]

Just a thought, but maybe you've got a crack in a solder joint in the DME. It wouldn't hurt to take it out and reflow the joints.

[thekidd]

The DME was a know good DME when I put it in. How would I go about resoldering the joints? Just getting some solder and puting it over the old solde joints? Every metal connecter? I have only soldered a guitar. I am in the middle of doing Razorbacks tests, I will try them, and then maybee take the DME out and re-solder tonight. I have an old chip (85.5 chip) that I can repace with the one that I have now (87 DME and AFM)

[thekidd]

Engine is running since I have started it when it was cold. Let it get to mid-range temp. and re-started about 5-7 timesand started everytime. Before I started the car, I tested the Coil and injecters. With the key on, I got .1 DCVs at the coil, and none at the injecter plug (#2). I tested these with the engine running and got at the coil .6 DCVs and .1DCVs at the #2 injecter plug. Havent got it to not start (HOT) yet to test if it is getting spark Razorback. I tried testing for spark when it woudlnt start hot, didnt get spark, and also tried to get spark from the coil (coil test from Clarks) but that didnt work either, but I probally did it wrong. I tried the "Y" jumper, and that didnt get the car started either.

Hot start- no start- 0 at coil (Black & Green wires) 0 at the injecter plug and 0 tach. bounce when I tried to start.

I am trying to reset the speed/reference sensor position, but its too hot for me to work in there. I read Clarks, he says that the allen head is a 6mm, but I coulnt fir my 6mm in there. I could fit a 5, but it didnt feel like it was in all the way. Tried to loosen it with the 5, and I dont know If I just spun the wrench, or broke the bolt. What size is the other bolt, its not an allen head wrench bolt, right?

[Razorback1980]

Something wrong there Steve....you should have 12 V at the coil black wire I think it is. Test this with the engine dead but the key on. If you don't have 12V there, then look to the ignition switch or connectors.

If it's starting, then you are getting spark so you don't have to test it then. Only test it when the car doesn't start.

Let's get the voltage we are looking for first...then let's worry about the ref sensors. If it's running, then the ref sensor gap is probably pretty close. The connectors may still be losing contact but the gap should be ok.

[thekidd]

So, this could possibly be the coil, ignition switch, or the plate behind the ig, switch? If I tested the igniton switch (resistance) the only test is to take it out and see if I am getting .2 ohms, correct? If I do get .2 ohms at the switch, then I would wanna check the "connecteor behind the switch" lie you said in your first post Razorback. How do I go about testing that? Couldnt find it on Clarks. Testing the coil, Clarks is confusing, you need 3 jumper wire- 1 for coil, 1 for spark plug, and 1 for (-) battery post. I just test the Green and black wire with my meter, correct?, and that should give me 12DCVs if it is good. I will let it get to the "HOT Start" and do these testes. I will give you numbers with the key in the "ON" position, then with the car not starting numbers with key in the "ON"

From StoogeMoe on Rennlist
Ok, so you have no spark when it's hot. Good. This problem should be a lot easier to find now. You can forget about the fuel stuff. The lack of spark is your problem. It can only be a few things now. Since you tried wiggling the reference sensors and that did not change anything, we can most likely rule that out. A possibility is that your coil winding is opening or shorting when it gets warm. You could test this if you had the appropriate tools to see if you're getting the trigger signal at the coil from the DME. If you were, then the coil is bad. If you had a spare coil, you could also swap that in for an easy test to see if the problem disappears.

But I suspect you are not getting the trigger. It is a known problem that the DME drive transistors for the coil and fuel injectors develop cracks in the solder joints from heat cycling over 20 some years. The cure is to resolder the joints to the transistors. The easiest way to know if this is the problem is to borrow a known good DME from someone and see if the problem goes away.

If you can't borrow a DME, then if you are knowledgeable about electronics or know someone who is, they can attempt to resolder the transistors, and see if that solves the problem.

Other obscure sources of this problem could be from the wiring harness shorting or opening connections due to expansion of metals when they get warm. Pray this isn't the case or it will take a lot longer to solve the problem.

Good luck!

[Razorback1980]

Steve,

The car doesn't have to be hot to get a good reading. Go to the black wire on the coil and put your meter on DC volts. put the key in the on position and put the red lead from the meter on the black wire and the black lead from the meter on the negative post of the battery. The meter should show 12V. Is this true?

If it is not true, then your coil isn't getting enough voltage and that is one problem but may not be all of them. DME does go bad sometimes as the guy on Rennlist suggested but it's usually last on the list because it's the hardest to test and isn't USUALLY the problem. Check the other components first.

It's true the coil CAN go bad but it almost never is.

[thekidd]

Tested the coil. No 12volt, I got 10.6 with the igniiton in the "ON" position, and I got 11.1DCVs with the engine running.

Got it to a "no start- HOT start" situation. With the key in the "ON" position the coil was getting 9.7DCVs with Black meter wire on (-) negative battery post, and red meter wire on black coil wire. I keep them connected and put the meter on my windsheild and tried to start the car. When I tried to start the car the voltage droped to about 8.3, but fluctating down to 7.3 to about 8.3 DCVs.

I will check to see if I am getting good resistance with the igniton switch (Im sure it is good, but just to pass some time) Clarks says ifit is .5 ohms or less it should be good when I turn the key with the switch out.

The starter was clicking very fast a few days ago, and still doing t today. I took the starter out once, and reinstaled it to try and fit the teath bettre. Still did it. I took it out agin, but I took the wire connecting the moter to the solinoid (big fat wire) off and twisted it to make it a thicker/ sturdier wire. Installed the starter, and still does it. I think when I bought the staeter, it was doing this after I installed it, but went away a few days later. Pointless, or usefull info, I dont know?

[thekidd]

Update- Before I started the car, I got the same numbers. 10.6 DCVs on the coil with key in "ON"position, and 11.1 DCVs with engine running. When the car wouldnt start, I left the key into the "ON" position, and check the coil, it was getting 9.0 DCVs, .7 less than last time I did the tests 2 hours ago.

[Razorback1980]

Steve,

The coil should have the same voltage as the battery or around 12V. Sounds like you have some dirty connections or grounds. Probably grounds, so look up where each of those are and clean them thoroughly and then coat with dielectric grease to keep corrosion away.

What do you mean by the starter was making a lot clicking? If this is the noise I am thinking it is, it's the starter solenoid clicking in and out because it doesn't have adequate voltage from the battery or adequate ground. Has nothing to do with the teeth on the gear. Take off the wires from the starter and clean them until they shine and coat them with dielectric grease as well and then put them back on. Next go to the battery terminals and clean those as well and use some kind of anticorrosion stuff on the battery terminals.

This should help the car but I'm not sure it's the problem yet. Let's try to battery voltage to the coil first.

[SuperXRAY]

Make sure to test a known good straight battery connection when you are doing your other voltage tests. The low voltage you are getting sounds like some bad grounds, or possibly bad power wire(s) to components. If you get 9VDC at the coil once, check it straight from the battery. If it's 12v (or close), then there is definitely a wiring problem.

[thekidd]

Cleaned the wires to te starter, didnty "click" when I first start the car, but did when it was hot and did not start. I also cleaned 5 ground wires (batter tray- both ends, behind the engine- just the firewall,couldnt get down to the engine bolt, the ones behind the headlights (2), and the one in the hatch. Couldnt find any more. When I checked the battery while running it was at 13.6DCVs, and then I checked the coil (black meter on (-) battery post and the black wire on the coil and I got 11.0DCVs. I keep checking a few times, and toward the end the coil voltage was at about 9.9 DCVs. When I got it to a no start, battery was at 12.3 DCVs, and the coil was at 9DCVs. I have no idea where to start if it is the wires going to and from. Think I may just goand get a used coil, and see what happens?

EDIT- Tried to start it again, left key in "ON" as always. The battery was at 12.2 DCVs, and I tested the coil, the coil was all over the place. I tested it a few times, and it went from 9.2- 10.2 9.2, 9.3, and lat 3 times was at 9.7 all when battery voltage was 12.2DCVs

[ballysdad]

Check batt voltage on the ignition side of the starter when it is hot . Make sure the car is secure and in neutral. Have someone turn the key to start and read the voltage. I am sure the heat shield is missing off your starter. The starter may be getting too hot to pass adequate voltage through the solenoid.

[Razorback1980]

Steve,

IIRC....The power goes from the battery to the big post on the starter. From the starter it goes to the ignition key and from the key to the black wire on the coil. Even with the lower voltage on the coil, that should be enough to start the car...although this still needs to be fixed. Continue on with the steps outlined above when it is in the no start condition. Make sure you have power at the injectors when the car won't start.

[thekidd]

I was wondering how the ignition system went, thanks. I tested/ inspected the switch, i got .2 ohms- I think it was terminals 50 & 30? I will check the starter in an hour or so when it cools and I get someone here to help me out and start? the car.
I did some check on the coil before I started the engine and when IT WAS hot no start.

OK, did the tests, but cant get a reading from the large post to green wire?
-2 small posts cold- .7
-large and green wire cold- "OL"
-2 small posts HOT no start- .7, but meter was fluctation from .6 up to 8.2 toped out, a few reading between
-large post to green wire HOT no start- "OL"

I will take the starter to PepBoys (local auto store) and have it checked after I do the starter test. If the starter gets too hot while driving around, will the car turn off? It did this last week about 15-20 mins into my drive. had my neigbor tow me home. Thanks guys, I appreciate it much.

[Razorback1980]

No, the starter will not cause the engine to not start unless the starter does not turn the engine.

It takes four things to make an engine run...spark, fuel, compression and timing. Since the engine runs cold, it can't be compression and probably not timing. After it won't start, check for spark by putting a plug in the plug wire and ground it on the intake manifold. If you have spark, then it's probably fuel related. Have you done this check already?

If you know it's spark related, then go down the list I posted first. Use a scientific approach, it will work better. We have voltage on the black lead of the coil even though it's not perfect. Next is to test for voltage on the fuel injectors. Have you done this both in a start condition and in a no start condition?

[thekidd]

I have done these checks. I have no spark when it is HOT and wont start. I tried doing the check from the end of the plug wires though when I first started the car, SPARK. But when it was HOT there was no spark.
Brother just got in and were going out for a little bit. When we get home I will check the voltage to the starter when cold and HOT. On the starter, I check the 2 wires that arent going to/from motor/ soleniod, correct? The voltage should be 12+, correct? And If the voltage is 12+, I will run it till it get to the no-start, and if it 11.9 then its a problem?

[Razorback1980]

So you have voltage at the coil and at the injectors? You may want to check all injectors as the injector harness is known to break occasionally. If you have voltage at both, then we need to check the wiring going to the reference sensors.