HELP NEEDED- (Another) 325 running problem

[bigwinn]

Hi all

I know, I know- Ive read the wiki, Trev and Malc are giving me pointers, but I wanted to post this up and see if anyone can diagnose from the video-



It starts doing stupid stuff at 0.18 sec and actually died the second after I stopped filming.

I've done the usual basic stuff, cleaned the ICV, checked the boot, tightened all hoses to check for leaks, especially the breather from the rocker. Airbox is fine, slidey thing in there seemed ok, plugs changed yesterday due to a slight misfire when cold with NGK's. I can hear clicking but not sure what I should look for with TPS stuff

The other thing is this only occurs when hot- its not a cold fault.

Where next? Blue temp sensor?

Cheers in advance

Stu[/youtube]

[Grrrmachine]

I'd say that's almost definitely a TPS issue if you're sure it isn't an air leak.

Trouble is, to clean and check it you have to dismantle a lot of the intake side of things, which is a ballache if you've just spent ages tightening everything up and using PTFE tape. Still...

Undo all the intake boot and all the other hoses to the throttle body. Don't under the water hoses feeding the throttle body heater plate.

You need a 10mm socket on a screwdriver style extension. Use it to undo the four nuts holding the throttle body to the intake manifold. Use a bit of blue-tak in the socket so you don't drop the nuts and lose them.

Once loosened, GENTLY pull the throttle body off its screws. Don't yank it, because it's still connected.

You need to pull it so that you can access the black plastic mechanism underneath, so try and turn it upside down. Once you have, check the condition of the little rubber blanking plug that's under there. That's Prime Suspect for air leaks, and if there's even the slightest hint of perishing on that bit of rubber, replace it.

If all that's good, get a multimeter and test the TPS according to the Wiki:

http://www.e30zone.net/e30zonewiki/inde ... ion_Switch

Whether it passes or fails, it's still a good idea to clean it out with carb cleaner and drill the hole that the Wiki suggests. Then reassemble everything, paying attention to the throttle body gasket and that all the ancilliary air hoses are well sealed in place.

[bigwinn]

Legend- thanks Grrrr

Stu

[bigwinn]

Dont suppose anyone has pictures of TPS so I can be doubly sure

[mcbonio]

Its underneath the intake manifold.

[Grrrmachine]

If he's just unbolted the throttle body, it'll be nowhere near the intake manifold

This is it:



But concentrate on the rubber bung under the throttle body first.

[bigwinn]

Nice one. I'll check the breather hose underneath too as that seems a common fault through perishing.

Would these faults manifest themselves more when at running temperature?

[daimlerman]

When cold,the engine gulps huge amounts of both fuel and air ,as it warms and the blue sensor does it's stuff,any air leaks start to play their part.

Still feel that £60 with Injectortune is money well spent,though!

[bigwinn]

Going for the blanking grommet tomorrow to see what state it's in

As it's had new plugs and it's getting a bit tappy I'll do the injectors when I fix the leak

[bigwinn]

Right

Had a good look over this today- as had time to look at it all

Checked TPS, clicking OK, took throttle body off and gave it a good clean, checked the vacuum hose to the head, checked blanking grommet, put it all back together again...

Started fine, ran very well.

Then when hot- temp up to operating temp, it started again- slight misfire leading to a full cutout on idle.

However, this time it wouldnt restart at all- left it for half an hour and it restarted and drove fine- as it was cold.

What next-

S

[aeberbach]

I went through EVERYTHING before trying this. I was 100% sure of no air leaks, had disassembled everything including TPS, spent hours checking electrical connections from engine bay back, replaced injectors etc. I even rigged a fuel pressure sensor I could see while I was driving because I thought it might have been fuel pump problems.

Remove your motronic box, disassemble it and reflow all the solder on every connection. If you can't solder or don't have the right equipment get someone to do it for you, should be no more than an hour's work.

It was the final thing that changed my car from a huge PITA that would randomly cut out on freeways to 100% reliable. Solder doesn't handle mechanical stress all that well and my theory is that 20+ years of driving vibration finally got something to fail intermittently.

[bigwinn]

Cheers mate

Did you try the blue/brown temp sensors before doing this?

[cecotto479]

I had one last week that did similar. It ran perfectly for about 5 minutes then started missing and wouldn't idle. After all the normal stuff and a blue temp sensor and a crank position sensor, a known good ECU fixed it.

If you can at least eliminate that.

[bigwinn]

Cps is ok. Blue temp sensor next

[Grrrmachine]

Please TEST the blue temp sensor before you replace it:

http://www.e30zone.net/e30zonewiki/inde ... ug#Testing

[bigwinn]

will do- thanks

[aeberbach]

Yep, checked blue & brown, still have the same ones today.

I agree that borrowing an ECU to see if it makes a difference would be a great idea, before trying the solder reflow.

[bigwinn]

Got a spare ecu so will try that as well.

[Grrrmachine]

Brown temp sensor is only for the instruments; it has nothing to do with the running of the engine

[bigwinn]

Right- its not the blue temp sensor- followed the wiki and the resistance was good when hot

Where next?

I'm not feeling the ECU bag as the next point of call

Gents?

[Grrrmachine]

I'm not feeling the ECU bag as the next point of call

I'm afraid I don't know what this means. Have you tested the Blue Temp sensor at the ECU?

[bigwinn]

An earlier post said to replace the current ECU with a spare

But I dont see how this will be affecting the running of the car when hot and not cold?

Tested the Blue temp sensor at the sensor as the wiki says

[Grrrmachine]

Wiki says test the sensor, THEN test at the ecu. This is to make sure the reading is getting to the ECU, since the wiring is a known weak point. If you've got corrosion at the injector loom plug (C191) then the ECU won't be able to read the blue temp sensor properly.

[bigwinn]

Ah- my bad

Tomorrow night then

[bigwinn]

Ah well at least the weather is nice. Tested and retested the blue temp sensor at the ecu. Checked 191 plug for corrosion. Changed dizzy cap and arm just in case.

Starts fine. Slight revs it's no problem. Gets to normal running temp and if under revs, it's all good.

Foot off the gas and it dies and won't restart

What next?

[SgHawk]

I had this exact fault, intermittent misfire and stalling when warm.
Had the same headache as you trying to source the problem too. Turns out my distributor cap had a crack in it along the bottom so spark 5 was grounding/jumping, causing the missfire.
Replaced the cap and leads, runs a treat!

Hope yours is as simple!

[bigwinn]

Will- spark is fine, when hot it seems to be overfuelling as it floods effectively then wont restart. leave it for 5 mins and it restarts

Sg- thanks bud, cap and HT done

Damn these intermittent faults

[bigwinn]

How do I check the efficiency and operation of the AFM?

[cecotto479]

An earlier post said to replace the current ECU with a spare

But I dont see how this will be affecting the running of the car when hot and not cold?

Exactly my thinking with the car I referred to. When I started it, I thought, "It'll not be the ECU." Two days later, I thought, "I wish I'd taken two minutes to swap out the ECU the day before yesterday."

[bigwinn]

Thought I had a spare ecu in the garage but no joy

[bigwinn]

I admit defeat- its now off to someone who can find it and fix it- I've done as much as I can with no success...

will update when I know what the issue was