320i m20 bad misfire ??

[magpie]

had a look at a 320i today that's not very well,it has a really bad misfire and wont rev up.It just dies out and backfires if any revs are given at all and it just about ticks over cutting out more than not.

things changed are afm and tps,i removed the black sooty plugs,cleaned and replaced them [all 6 sooty] and the tps has been removed and cleaned out but still no joy,it's still got the bad misfire and is un-drivable .

i have a known good throttle body with tps and another ecu that i might swap over but fear i'm wasting my time as it could be something completely different like possibly the cps , [could this cause the symptoms] or would it just not start at all if this were not working and how di i test it ? another thought is possibly the timing belt has jumped a tooth [unlikely ?]

advice appreciated as i'm getting fed up now .

[Brianmoooore]

Checked the blue temp. sensor resistance at the ECU plug?

[eko]

Injector loom connector below inlet manifold?

[magpie]

Checked the blue temp. sensor resistance at the ECU plug?

all i've got is a multimeter ,do you mean the plug with two wires going to it next to the main ecu plug ?

tell me how i go about testing this as i've not had to work on an m20 before,it's all rocket science to me

i've given all the main plugs a check tony .

[maxfield]

Basically, set multi meter to resistance. Remove panel under steering wheel unplug ecu connector and put probes in the 2 wires that go to coolant temp sensor. 39 and 44 is it? Sure it tells you in wiki.

[Brianmoooore]

The C191 plug under the intake manifold is often a cause of issues with poor running if it is corroded. Check this carefully.

Do the checks at the ECU plug before touching this, or anything else. Nothing's more fun than trying to sort car electrics that have had a few extra faults introduced in addition to the original by someone blindly poking around
.

[Speedtouch]

Pins 24 and 45, according to the Wiki:
http://www.e30zone.net/e30zonewiki/inde ... emp_Sensor

[magpie]

i'll be having another look at the car next week so i better dig the multimeter out ready .

cheers.

[magpie]

stupid question....do i need the ignition on or off when checking ?

[Alex]

Dissy cap and Rotor arm any good ?

I was at RM2186 (Mikes) a year or two ago, and his south african Moredoor ran like a bag of shite, back firing through a scorpion exhaust, was fooking loud. didnt rev and struggled to start.

Iirc it was down to a fooked dissy cap and rotor arm

Its not the old donk from my Turd is it in big reds car ?

[magpie]

Dissy cap and Rotor arm any good ?

I was at RM2186 (Mikes) a year or two ago, and his south african Moredoor ran like a bag of shite, back firing through a scorpion exhaust, was ********* loud. didnt rev and struggled to start.

Iirc it was down to a fooked dissy cap and rotor arm

Its not the old donk from my Turd is it in big reds car ?

no not that car Alex. the dizzy cap etc have been replaced on this black 325i facelift moredoor

[magpie]

some silly questions for you who know auto-electrickery ....

is the meter set to do the tests above ?





are the pins right ?



i'm going to have a look at the car again this morning so hopefully i might be a bit closer to fixing it ....

i could always just offer him £350 and frag it instead !

[Brianmoooore]

Knob needs turning one notch anticlockwise, and red plug should be in the middle socket.

[magpie]

champion,

[magpie]

Getting 0.95 from blue sensor and 0.54 from cps ....

[magpie]

The reading for blue sensor is creeping up 1.17 maybe as it cools down ? Also the car seems to run a bit better as it gets warmer

[Speedtouch]

At what temperature was the blue temp sensor reading showing 0.95? When hot, it should be at around 330 ohms, which would give a reading of 0.33.

When cold, it should measure around 3300 ohms, which will give a reading of 3.30.

So, yes, 1.17 indicates that it's cooling.

[magpie]

at 0.95 the temp needle was still in the blue on the gauge and the 1.17 slowly going up was about 3 mins after the 0.95 reading was taken. when the car was up to temp it read 0.32

[Speedtouch]

Well, that sounds OK. And what does it read once you've left it to cool down?

[magpie]

no idea ,he ordered a blue temp sensor and said he would fit it himself and let me know the results

[Brianmoooore]

The full temperature reading for the blue sensor is correct at 0.32, so I don't think you new sensor is going to help!
CPS reading is correct, but that doesn't prove its good. An incorrect reading, however, proves it's duff.

[magpie]

hmm ,looks like i'll be going back then .

[magpie]

the new blue temp sensor has done nothing and the owner has given up and now sold it to me .

isn't it ironic that i've just sold an excellent high comp m20 b25 with 101k miles out of an auto ...dont ya think

well here's a quick vid of it running,or trying to .
it takes ages to start for the first time ,i'll take a look at the dizzy cap and rotar arm when i get a chance, even though the previous owner said they had been changed just before he bought the car thee cap could still have failed .

[youtube][/youtube]

no doubt i'll be back with some more questions

[AlpineCab]

I think you say youve looked at the CPS, but did you actually physicall inspect / clean it?

Had exact same problems with mine, turned out the CPS was badly f**ked.

Happened progressivley, and got to state where car would not start.

(and wires need to be intact, and not eaten by the radiator fan as they were in my case due to some tool "mechanic" not putting back the protective plastic cover thing, but sounds like yours are sending a signal to the ECU).

[Rav335uk]

Is that backfiring too??

[magpie]

Is that backfiring too??

yes rav,big bangs out of it's arse end

i'm sure we can fix this donk

[Rav335uk]

AFM been messed with?

[magpie]

no mate and i swapped it for a 325i one along with the icv,cleaned out the tps,it's got a brand new blue temp sensor and still no joy .fooking scrap lol

[Rav335uk]

have you tried a compression test

[magpie]

And how would I do that then ?


Anyway all the more probable causes need looking at first

[Speedtouch]

A compression test is one of the first things I'd do, to check for any head gasket leaks.

I recommend the Gunsons type, available from Halfords, etc.:
http://www.google.co.uk/products/catalo ... CEAQ8wIwBA