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Engine cutting out

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sideshowbob
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Joined: Mon Aug 01, 2011 2:18 pm
Location: Hampshire UK

Engine cutting out

Post by sideshowbob » Sat Dec 04, 2021 6:13 pm

I have posted on here before about this problem.

In essence my '88 635 CSi has developed a fault of when warmed up cutting out.

Due to Covid the car has not been used much and during this period in an effort to solve this problem I have systematically replaced the crankshaft sensor ( with a quality one), throttle position sensor, fuel pump relay, the idle control valve and the ECU with a rebuilt unit. The rebuild being undertaken by ATP Electronics.

Yesterday I undertook a long journey with the car to Fritz Bits to finally have the auto box removed and a reconditioned Getrag 5 speed manual installed. Reconditioned by All Gears, Worsop.

The journey was approx. 110miles. The car started and ran perfectly until at about 40 miles the dreaded cutting out manifested itself.
When I say cutting out it is momentary, the car does a little shudder, the economy guage swings rapidly to the left (infinity) and then everything returns to normal, over the next 4 miles it did this four or five times.
Then something different happened, while driving at about 60mph, I suddenly felt a loss of power and the engine did not respond at all to the throttle pedal, in fact the more I depressed it the more I felt I was loosing power, speed dropped to about 40mphand the car continued to drive at this speed with no response to the throttle, it slowed on slight inclines and speedd up on declines. It felt as though it was in "limp mode".

Eventually I pulled over into a layby and noted the engine sounded as though it was firing only on 4/5 cylinders. I turned the engine off and after a few seconds restarted it
It fired up instantly and we completed the final 60 miles of the journey cruising at 70 /75 mph with no cutting out or loss of power.

At no time did any warning lights come on.

I am now at a loss as to what is causing this and wondering do I have a fractured wire in the electrics somewhere, if so, anyone have an idea which wire would cause such a massive failure or as I suspect do I have a problem some where in the fuel supply or possibly an AFM fault.

Has anyone else experienced such symptoms

Any help or ideas gratefully accepted

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86_6series
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Joined: Mon Apr 02, 2007 10:08 pm
Location: West Nyack, NY

Re: Engine cutting out

Post by 86_6series » Sun Dec 05, 2021 1:32 pm

I had similar symptoms and it turned out to be the temp sensor.
Don't just replace it on my suggestion, confirm thru testing that
it needs replacing. Good luck.

https://www.eeuroparts.com/Parts/348924 ... 621709967/

sideshowbob
Bigcoupe 100 Post club
Posts: 191
Joined: Mon Aug 01, 2011 2:18 pm
Location: Hampshire UK

Re: Engine cutting out

Post by sideshowbob » Mon Dec 06, 2021 5:19 pm

That's very interesting, hadn't thought of that, could explain why these symptoms only manifest themselves after the car has warmed up.

I will try and source one and get it fitted.

Ever hopeful

Thanks again

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86_6series
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Joined: Mon Apr 02, 2007 10:08 pm
Location: West Nyack, NY

Re: Engine cutting out

Post by 86_6series » Tue Dec 07, 2021 1:06 pm

Please let us know if it is that switch.

Thanks

Candycj1
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Joined: Thu May 17, 2018 10:22 pm
Location: London

Re: Engine cutting out

Post by Candycj1 » Thu Dec 16, 2021 10:36 am

I too have posted here about my 87 highline running issues having also replaced all sensors, lines, pumps, filters, regulators etc - and had both the original ECU and a spare tested and signed off by ATP. Eventually i sent her to Classic Heroes as i'd run out of ideas; they phoned the next day to say they'd swapped out my ecu with one from a running vehicle they have there of similar vintage and it runs perfectly - put my (tested) ecu back in, car won't run. i sent them the spare unit which they confirmed exhibits the same issues. They're now awaiting a replacement which will hopefully arrive today.

Not saying this is your issue - and i've not spoken to ATP about this yet - just don't rule it out even if it has been bench tested!

sideshowbob
Bigcoupe 100 Post club
Posts: 191
Joined: Mon Aug 01, 2011 2:18 pm
Location: Hampshire UK

Re: Engine cutting out

Post by sideshowbob » Sat Jan 15, 2022 10:44 am

Yesterday I picked up my car from Fritz Bitz having had the auto gearbox removed and a rebuilt (AllGears - Worksop) Getrag 5 speed manual installed.

Additionally Rich checked out what was causing the misfire and loss of power after the engine 'warmed' up.

Previously various garages have replaced crankshaft sensors, idle control valves, throttle position sensors, fuel pump relay and reset the AFM, all to no avail.

Rich seems to have cured the problem.....faulty injectors on number 2 and 4 cylinders. He identified they were running lean if at all, this manifested itself in the manifold having raised temperature on the two offending cylinders. He replaced both injectors and problem seems to be solved.

I picked the car up and drove 110 miles along 'A' roads and low and behold no misfire.

The 5 speed gearbox has transformed the car, I can now fully control the power delivery, like change down from 5th to 3rd to overtake instead of the ridiculous 2 stage 'kickdown' which literally gave you a 10 second power surge.

Also by using the gears sensibly I think the fuel consumption has improved.

Retained the original Auto LSD diff and now at 2250 revs car is doing 60mph in 5th and at 4000rpm is doing an indicated 100mph in 5th.

It has a 15lb flywheel which presents no problems in pulling away in 1st gear, and will pull comfortably from about 1200rpm, 25 mph in 5th.

So this mod. along with the Fritz stainless manifold, stainless exhaust and his modified ECU chip has transformed the car.

Next job all new suspension bushes and Bilstein B6 shocks on standard springs.

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