Ignition issue 87 N/A

[NiGMa]

Hi folks,

I have searched all over the forum and haven't seen anyone with this particular issue, although it sounds similar to what some people call "heat soak".

Problem:
My car will not start after having driven for 30mins. It WILL start with no problem, consistantly at the start of each day, or if it has been sitting at least 15mins after driving. It will NOT start up after driving for longer periods. For example, if I drive somewhere and it takes 30mins, turn the car off, it will not start until I wait about 10-15mins, but then it starts up fine, no weird bad running or missing or any issue. If you try start it within that window of 10-15mins, it cranks fine, but there is no ignition, but when it finally reaches that magic spot of 10-15mins and you give it another crank, it fires right up and runs perfect.

So my supra friends, what the? is this a ignition issue?

I did do a spark test as described in the TSRM, where you get someone to crank and you hold the end of the ignition lead that goes to the distributor near the chassis and watch for sparks. I did this while it wasn't starting and noticed inconsistent arcing. Does this confirm that it is an ignition issue, or could it be something else?

EDIT: Oh, and also, I have done the fuel pump test to see if this problem is fuel related. That is, when I having this problem one day, stuck in a car park, I connected B+ and FP I on the diagnostic block, I heard the fuel pump whirring, left it like this for 1min so as to build up pressure.... and then disconnected it, tried to start car and got no start. But again, all I had to do was wait and then it started up.

Thanks.

BTW, this problem has been getting worse, I could put up with it before as it would only do it on really hot days, now its doing it all the time. Time for a solution me thinks. =)

 

[Nick M]

Can you check actual fuel pressure when it won't start? You need a pressure gauge and adapters to fit the rail. There isn't a schrader valve. :nono:

http://www.autoshop101.com/forms/h22.pdf

Page 9 of 22.

Keep in mind, an old fuel pump may also struggle to prevent vapor lock. Even though the car runs fairly normal.

Make sure you have these parts, and they are hooked up according the vacuum diagram. Many previous and current owners take things off the car they think it doesn't need. Like this valve. I just noticed Austrailia. Your engine control might have small differences from the North American market.

 

[NiGMa]

Thanks for that. I don't have those parts installed, they took them off after the rebuild.

So youre saying this could be my problem? I'll put it in today and see how it goes.

If I understand what youre suggesting correctly, my problem would be that as I drive my car warms up to operating temperature, I turn it off and somehow the fuel pressure doesn't hold and so if I try start it for the next 10mins it wont start. But if I install this FPU VSV then it will get the pressure up to normal while I'm cranking and running for upto 2 mins.

Wouldn't there be even more pressure as it so hot underthere and for the first few mintues, the temperature under the hood actually increases because theres no air cooling?


Any body else got an idea?

 

[NiGMa]

hang on, this doesn't make sense, the FPU VSV system will increase the pressure, but if I manually ran the fuel pump when I had this problem as it didn't solve the problem, doesn't that mean its not a problem with the fuel pressure?

 

[NiGMa]

After some reading, I just realised that a 7MGE doesn't have a FPU VSV. So there goes that idea.

 

[jetjock]

No, they don't have the FPU system. Your problem could still be a loss of rest pressure although pressurizing the fuel system should have eliminated that possibility. I'd still take Nick's advice to be sure however...

 

[NiGMa]

No, they don't have the FPU system. Your problem could still be a loss of rest pressure although pressurizing the fuel system should have eliminated that possibility. I'd still take Nick's advice to be sure however...

Actually, after looking at a wiring diagram, I noticed I have the connector with the right colour wires for a FPU VSV, and I've got a spare vsv that was probably connected there, so I hooked it up. Could it be that the australian versions had a FPU system? My car has a oil cooler also, even though its only an N/A it was an australian change for the hot weather I've heard.

Anyway, now thats its connected, I'll see how it goes. =) I'll be back

Thanks for the help guys.

 

[3p141592654]

87-88 7MGEs have it. At least it in the TEWD and the software in the ECU supports it.

 

[Nick M]

I just wanted him to see why the car doesn't run with old age until it cools a bit. If it starts and is running sort of rough, pull the vacuum line off the fuel pressure regulator. Be sure to pinch the vacuum hose.

If you car magicly runs noticably better with more fuel pressure, then you need to do the pressure test.

 

[NiGMa]

OK, I still have the problem. So the FPU VSV didn't fix it, although my fuel economy went down, I guess because it confused the computer as I dont have a vacuum leak anymore.

So what now guys?

 

[Nick M]

Have you checked fuel pressure yet?

Can you check actual fuel pressure when it won't start? You need a pressure gauge and adapters to fit the rail. There isn't a schrader valve. :nono:....Keep in mind, an old fuel pump may also struggle to prevent vapor lock. Even though the car runs fairly normal.

 

[NiGMa]

No, I dont have the tools to do that, or the know how.

I thought it couldn't be fuel pressure because of the test i did by connecting FP and B+ when I was having the issue, I ran the fuel pump for 1min and it still didn't fire.

Also, I noticed something the other week. I was working on the car in the garage, and by mistake I left the ignition on "ON", not accessories, but the next one, for about an hour. I was finished and had to move the car, but it wouldn't fire up, it just cranked, same problem as when I've been driving for a while, but this time the engine wasn't actually running. So I put the ignition to "OFF" and left the car for 10mins, it fired up no problems this time.

??? doesnt this sound like an ignition issue???

 

[Nick M]

If you have a weak fuel pump, it won't matter if you short B+ fo Fp in the diagnostic box. Think about it.

Now, I don't know that is your problem. I haven't seen your car.

A car doesn't start for one of three general reasons. And it isn't air-fuel-spark.

The combustion triangle is air-fuel ratio, spark and compression. One of those three is off. Since it starts better cold, it probably isn't compression. There is a specific check for that, but you would do last based on you hard hot symptom. Spark check is easy. Pull the number one wire, but leave the plug. Put a spare plug in the wire terminal and ground it. You don't have to buy an over priced spark tester. You can make one with 18 guage wire, alligator clips, and solder. Ground the spark plug and have your buddy crank the engine over when it won't start.

The spark should be very bright with a slight blue tint. If you have no spark, I would personally check a known good ignitor.

 

[NiGMa]

Hey Nick, thanks a heap for your help, its much appreciated, God bless you.

I see your point about the weak fuel pump.

I will try that spark test.

Are you saying that I should borrow someones good ignitor and swap it into my car and see how it goes?

Whats the difference between an ignitor and the coil? could you explain, or could you point me to a link?

Thanks!

 

[Nick M]

The ignitor is the rectangular piece of metal that has a metal fins on it. That is a heat sink, if you don't know. The ignitor is a solid state trigger device for the coil. Unless jetjock (or 3P) has a better description.

The ignitor turns on the coil at the command of the ECU signal which is the IGt signal, ignition trigger, or timing, depending on which book you are looking at. Same meaning though. Transistors are used because they can switch on and off a whole lot faster than a relay, giving much more accurate ignition timing.

If you can't check for fuel pressure, you can check for spark as I showed. Just use the number one wire, that is the only one you need to pull. See if you have spark when it won't start. If you do, move to fuel. If you don't, we move forward from here.

There isn't an ignitor test in the repair manual. Although I am sure there is one you could do. That is why it is easier to just just swap them to check. But if you don't have spark there are many other checks to make. I suggest it because of the age of the car, not because it should be a priority check based on a diagnostic flow chart.

 

[3p141592654]

It does sound like something that is not working when it gets hot. Have you checked for codes? A bad ignitor would normally set one.

 

[NiGMa]

The ignitor is the rectangular piece of metal that has a metal fins on it. That is a heat sink, if you don't know. The ignitor is a solid state trigger device for the coil. Unless jetjock (or 3P) has a better description.

ITS LIKE A MOSFET!!!! I GET IT!! AWESOME, that makes perfect sense, thank you.

ok, so I did the spark test and I got nothing, I even tried just the main ignition lead that goes from the coil>distributor and I got nothing. So... is it safe to say i need a new coil? or is it the ignitor? I don't know. :1zhelp::aigo:

oh, and of course after 10 mins when I tried again, surprise, surprise it sparked!

 

[NiGMa]

If you have no spark, I would personally check a known good ignitor.

I don't have a known good ignitor. Nor would I want to get another 20+yr old one from the wreckers.

 

[NiGMa]

Okay, I'm trying to get a second hand ignitor and coil, see how that'll go. I did the TRSM Multimeter test and got weird results.

Also, I did some more digging, and someone on a corvette forum has identical problems to me, it turned out to be his wiring, interesting.. I dont know how I would go about checking mine though, other than getting a multimeter to both ends of a wire, show the Ohms, and then get a hair dryer and blow it around... lol, because the problem is definately related to heat, though its not by the engine heat because it happens even if I leave the ignition switch set to ON for more than 20mins, meaning the electrical circuit gets warmed up until a point where it cant feed enough power through to the ignitor, hmm.... any ideas?

Either way, I should have a second ignitor and coil to test soonish.

Peace

 

[NiGMa]

Ok, new info:

I get a code 11 everytime this happens!!!

Today checked for codes and I had a code 11, I remember seeing this in the past and it annoying me because its not listed in the manual, so I looked it up in the forums, and there were plenty of explainations to what is was, I read that the wiring could be bad someway along to the ECU, so today, I took JetJocks advise and grounded the ECU ground wires that are on the intake manifold to the ignitor mount with a thick wire, and then took another thick wire and connected from the ignitor mount to the chassis ground point just behind the battery that the negative terminal grounds to. Hoping this would sort out the "ECU no having enough power" problem.

Then I reset the computer by taking out the EFI fuse for 1min. This cleared the code. I wanted to see if I could get the code again, so I went for a quick 10min drive came back turned the car off and checked for a code, I got the normal fast flash, all is well... then I tried to start and the car started fine.

Then later, I went for a 30min drive, enough time for the hot-start problem to occur, came back home, turned the car off, checked for a code, got a normal blink, all is well.. waited about 2mins, tried to start the car and as usual, it did not start, no suprise, so I checked for a code, and got a normal blink... then I waited another 5mins(as I normally have to for it to start again), and it started! then I shut the car off and checked for a code, and guess what... I got a code 11!!! So whatever problem I have with the hot-start issue, seems directly related to code 11!!! We have progress.

Any thoughts folks?

It feels like I am finally getting somewhere with this.

I decided against getting another ignitor and coil as its not going to be cheap and basically everything I read tells me bad ignitors dont behave the way my car is behaving, different symptoms. I never have the car turn off on me, no missing at any rpm, etc. And we've already established that its not a fuel issue, so this code 11 seems to be it! =) =D