Have an issue with my m30. First, it's quite slow to start. It has to be cranked for a few seconds, then it starts clicking and fires up. I think the clicking is the fuel injectors firing but there is a delay.
Secondly there is a misfire which has been getting worse, with performance dropping off a fair bit to the point an m20 powered car is faster.
Last night I changed the crank sensor as the one on it was looking very sorry for itself with the wire frayed where it enters the sensor, however this has had no effect.
Furthermore it is also running very rich. My garage stunk of petrol after firing it up for a minute.
Any ideas? I need to test the blue temp sensor as that might explain the richness. Other than that, I'm wondering if the fuel pump relay might be faulty which might explain the delay in starting. Any input is greatly appreciated. Plugs were new >1000 miles ago.
Thanks
Ross
Slow to start/misfire
Moderator: martauto
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Brianmoooore
- E30 Zone Team Member
- Posts: 49353
- Joined: Mon Jan 10, 2005 11:00 pm
If you think the injectors are messing about, then that's likely to be the DME relay. Link it out with a couple of pieces of wire from pin 30 to both 87s as a test.
Testing the blue temp sensor, both hot and cold, and preferably at the ECU plug, and hooking up a fuel pressure gauge to check what's happening before the car is started, when it's running, and after it's stopped will also be useful.
Testing the blue temp sensor, both hot and cold, and preferably at the ECU plug, and hooking up a fuel pressure gauge to check what's happening before the car is started, when it's running, and after it's stopped will also be useful.
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ross_jsy
- Married to the E30 Zone
- Posts: 7307
- Joined: Sun Jul 12, 2009 11:00 pm
- Location: Jersey, C.I.
So I got all the way out to my workshop to find my multimeter was out of battery. It was fine when I used it on the weekend! 
However I tried a few things. First, I swapped the DME relay for a known good one. Same issue. Then I swapped the FPR for a known good one thinking that if it was failing, it could be letting fuel past when the ignition is off, meaning it takes a while to build pressure again. However same fault.
To check that the clicking was the injectors as I suspected, I removed the fuel relay. No clicking. So this has lead me onto a theory. The engine had been sat for almost 15 years before it was installed. All the fuel lines were utterly shot. I'm thinking that some old fuel has varnished up the injectors, causing them to leak down once the ignition is off, losing pressure in the fuel rail, and would also explain the general poor performance and massively rich running.
A couple of things support my theory. The first time you fire it up after it has been sat, say overnight, is always the worst. The engine runs really rough for a few seconds and if you try and rev it it won't respond much at all till it clears, and will occasionally pop. It has also backfire once or twice.
Also, if you shut the engine down once it has been running, but start it up again quickly, it starts right up as there is still pressure in the fuel rail. The injectors are also incredibly loud. Far louder than an m20. Whether that would happen from gummed up injectors, I don't know.
I'll borrow a fuel pressure tester, and also pull the rail out and prime it and see if they leak at all. Either way, the injectors are 29 years old so they need a refurb
However I tried a few things. First, I swapped the DME relay for a known good one. Same issue. Then I swapped the FPR for a known good one thinking that if it was failing, it could be letting fuel past when the ignition is off, meaning it takes a while to build pressure again. However same fault.
To check that the clicking was the injectors as I suspected, I removed the fuel relay. No clicking. So this has lead me onto a theory. The engine had been sat for almost 15 years before it was installed. All the fuel lines were utterly shot. I'm thinking that some old fuel has varnished up the injectors, causing them to leak down once the ignition is off, losing pressure in the fuel rail, and would also explain the general poor performance and massively rich running.
A couple of things support my theory. The first time you fire it up after it has been sat, say overnight, is always the worst. The engine runs really rough for a few seconds and if you try and rev it it won't respond much at all till it clears, and will occasionally pop. It has also backfire once or twice.
Also, if you shut the engine down once it has been running, but start it up again quickly, it starts right up as there is still pressure in the fuel rail. The injectors are also incredibly loud. Far louder than an m20. Whether that would happen from gummed up injectors, I don't know.
I'll borrow a fuel pressure tester, and also pull the rail out and prime it and see if they leak at all. Either way, the injectors are 29 years old so they need a refurb
