IRRATIC START WHEN COLD

From 16v to vr6- Add all the information in here....

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pointer
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Re: IRRATIC START WHEN COLD

Post by pointer » Sun Jun 02, 2019 11:11 pm

Thanks, just to be clear, the distributor cap is on correctly as that will only go on one way! It is the position of the leads them selves within the cap that I was describing.

I will have a look to make sure the other aspects you refer to are OK, but as I haven't changed anything as far as the distributor body is concerned I suspect that they will be OK.

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fonzooorooo
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Re: IRRATIC START WHEN COLD

Post by fonzooorooo » Tue Jun 04, 2019 4:42 pm

Just checked in on here for the 1st time in months!

Some of these SPIs are REALLY fussy about ignition timing - the ECU learns when the spark is, and regulates to suit... Those need plugging into vagcom to set up. (yes, really - we've got a mk3 cabrio that does - and when it was out after a dizzy replacement it'd be cranking, cranking cranking before a ropey warmup and sub-optimal running) ... I'm not 100% sure if the RP is like that though!

If you've still got no spark though, there's only really the coil, plugs/leads and the hall sender in the distibutor (which itself is not uncommon to fail!)... If you've changed the coil and it's dodo dead, I'd go hall sender next - I've seen them as a seperate part, or you could replace the whole dizzy.

With the engine set to TDC, and the dizzy cap removed, the rotor arm should point toward the back and its centre should point to a little notch in the casing... If that's the case, #1 plug lead should come out above that, then 1342 clockwise from there.

If you DO have a spark, the usual suspects for funnny running or warmup are coolant temp sender, then the rubber mount for the SPI unit which crack and let air in, throwing the mixture out.

Copious carb cleaner will clean out the SPI unit (which CAN fail, but it's rare) ... Worth unplugging it again and lashing a load of electrical cleaner in the plugs (and obviously making sure they're REALLY seated) too, especially if it's all a bit oily and dirty.
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pointer
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Passat model: 1741 estate 1991

Re: IRRATIC START WHEN COLD

Post by pointer » Tue Jun 04, 2019 10:38 pm

Thanks for that, something to chew on.

Two queries

1 What does SPI stand for?
2 Is there any way of checking a hall sender, I only have a multimeter? :-??

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Alan Gunn
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Re: IRRATIC START WHEN COLD

Post by Alan Gunn » Wed Jun 05, 2019 6:14 am

Single point injection well i think it is.
Not sure if you can test the hall-sender.
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fonzooorooo
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Re: IRRATIC START WHEN COLD

Post by fonzooorooo » Fri Jun 14, 2019 4:09 pm

Sorry for the delay - I'm totally out of the habit of checking up on here(!)

Yes, Single Point Injection

I've never actiually tested one - I've always been in the poistion of having a spare or 2 knocking around.. not sure I have any more though! ... Anyway, A moment on Google found this on ClubGTI:

Hall sensor:
1 Check that the ignition system wiring and plugs are fitted correctly.
2 The coil and TCI-H unit must both be in good condition.
3 Pull the HT lead from the centre of the distributor cap and earth it to the engine or
bodywork.
4 Pull back the rubber boot from the switch unit and connect a voltmeter between terminals 6 and 3.
5 Switch on the ignition and turn the engine by hand in its normal direction of rotation. The voltage should alternate from between 0 and a minimum of 2 volts. If not, the sender is faulty and must be renewed.

(Not something I've tried, so can't guarantee, but as you're only measuring voltage, I can't see how it'd fry anything!)
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fonzooorooo
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Re: IRRATIC START WHEN COLD

Post by fonzooorooo » Fri Jun 14, 2019 4:12 pm

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Stringed musical instrument making and repair

pointer
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Re: IRRATIC START WHEN COLD

Post by pointer » Sat Jun 15, 2019 5:07 pm

Sorry I haven’t been in touch but my son and his partner Liz have been over from Australia and we have been out and about a lot recently although I have tried some work when I could.
As the coil distributing company has dismissed any thoughts of mal-function, I re-started investigating elsewhere.

1. Having replaced coil, distributor cap, rotor arm, leads and spark plugs with no improvement, I even used jump leads from my other car in case the voltage was too low, but that didn’t help.
2. As I am getting very frustrated, I decided to let my local garage investigate, so I contacted RAC to help out and possibly tow me to the garage.
3. After carrying out several checks including if fuel pump was running, the operative stated that he thought the spark was quite weak, but he opened up the SPI. To my amazement, he found that one of the pins on the internal injector was bent ! (Clumsy me!!) He straightened the pin and replaced the SPI. This time it started and seemed OK. :ymhug:
4. Next day I tried to start the car but it took a few turns before firing. I switched off after a few minutes and tried to restart immediately, but no joy. :-q I contacted the RAC again and they arrived within the hour, different chap. He found there was plenty of fuel getting to the SPI although he agreed that the spark was on the weak side.
5. As he could not find anything obvious, I mentioned I had a 2nd hand Motronic ECU and should we give that a try. This we did and the car started although a little lumpy. We switched off and tried re-starting and this time it did start, so RAC chap felt he had done enough. I then contacted my local garage and agreed for them to take charge!! x_x
6. Next day the car started but was quiet lumpy and would stall if I took my foot off the pedal. I had a harrowing drive into town and left it with them. Once they have had a look, I will update this thread.

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