Coil replaced - still not good - help

miles5 · Post by **miles5** » Wed Apr 22, 2009 6:54 pm

The story so far:

Bought 911T 3 weeks ago and drove back from Belfast etc....

Washed car following weekend - conked out after 1/4 mile. Started again after two hours

Washed car weekend just gone - would start at all. RAC came out, tried lots of things, poped a new coil (not correct type), engine started (turned off quickly as not the correct coil). Diagnosis get a new coil.

Today collected new coil (permatune) from Tuthills and popped it on. Started, initially ok, then ran rough and stalled. Did it a few times, then realised hand throttle up a little. Tried again ran absolutely fine. Let it run for few minutes, then set off.

5 miles up the road pulled in for petrol, fluffed as revs dropped. Started ok again, a little rough on acceleration, then cleared. 8 miles later slow down for roundabout fluffs alot, but keeps going. Heading for home running a little lumpy, but going up the rev range. As slow down in the village - massive back fires, rough running, crawl up the drive (whole village now know I have a nice new yellow car that doesnt work very well!!). Car dies.

Restarts runs rough with occasional back fire.

Any ideas on what the story may be. Any help appreciated.

PS. No jokes about washing cars too much!!

Histrally · Post by **Histrally** » Wed Apr 22, 2009 7:26 pm

Your problem could be assocotiated with a lot of things electric or fuel related and it will take a systematic search through each system to check the correct function of both
Has the car been sitting unused for a long time?
I can tell you of a problem I had soon after picking up my car which had not been used very much for four years. It ran OK for a while then starting losing power until it just stopped. After a short while it would restart, run for a couple of minutes then stop again. I traced it to the fuel filter in the engine compartment. (Mechanical fuel injection on what was then a 2.4) The tank obviously had a lot of dirt in it and it was blocking the filter. After stopping the dirt would drop away and allow enough fuel through for a short period. Changing the filter cured the problem Well filter No 2 did the first repacement leaked at the crimped section. When I looked inside the old filter you could see the rust etc.
Hope that helps.
Jerry

KS · Post by KS » Wed Apr 22, 2009 8:09 pm

I know it seems unlikely and too simple, but check the state of the points – see if there's even any gap – as they closed right up on my MFI Carrera and it behaved like the fuel pump had packed up, ran roughly, backfired, you name it... Just a thought before getting too carried away.

mycar · Post by **mycar** » Wed Apr 22, 2009 8:48 pm

Just to add to Histrallys post, I had the same problem with dirty fuel. If this is indeed your problem, you should consider cleaning and relining your tank, it`s amazing how much rubbish can get through the filter, especially after a spirited drive.

Mike.

mrg3.6 · Post by **mrg3.6** » Wed Apr 22, 2009 9:17 pm

KS wrote:I know it seems unlikely and too simple, but check the state of the points – see if there's even any gap – as they closed right up on my MFI Carrera and it behaved like the fuel pump had packed up, ran roughly, backfired, you name it... Just a thought before getting too carried away.

This is good advice and I know, having spent nearly two months buggering around with coils & CD units only to discover that a new set of points sorted the problem

Martin

Rich Lambert · Post by **Rich Lambert** » Wed Apr 22, 2009 11:26 pm

mrg3.6 wrote:
KS wrote:I know it seems unlikely and too simple, but check the state of the points – see if there's even any gap – as they closed right up on my MFI Carrera and it behaved like the fuel pump had packed up, ran roughly, backfired, you name it... Just a thought before getting too carried away.

This is good advice and I know, having spent nearly two months buggering around with coils & CD units only to discover that a new set of points sorted the problem

Martin

It cost me a very expensive tow bill to find out my points had closed up...fixed it at home in 2 minutes. Same symtoms as described.

mycar · Post by **mycar** » Thu Apr 23, 2009 5:59 am

Mike.

Getting a bit previous, thought the problem was cured, it was early.

Vic Cohen · Post by **Vic Cohen** » Thu Apr 23, 2009 8:05 am

Sure only way as someones said go through the lot systematically..........after non use , big bangs , etc any smoke ? i Had cold start valve breaking up cause very similar , never stopped completely but choked the thing to very slow ,undriveable

Detail perhaps i had mega coil probs with Mr Bosch ...like 4 new ones in a a year / abt 6000miles .......in my experience they work or they dont ...NOTHING IN BETWEEN ....I MEAN DEAD STONE DEAD!

miles5 · Post by **miles5** » Thu Apr 23, 2009 9:36 am

I have a slight suspicion about fuel filter - looks a little grubby (however that is partly comparsion as the rest of the car looks pristine). The tank itself looks perfect on the outside - no knowing about the inside.

Points are opening and closing just fine.

Process of elimination is the only way!

Many thanks for input.

Patrice · Post by **Patrice** » Thu Apr 23, 2009 3:28 pm

KS wrote:I know it seems unlikely and too simple, but check the state of the points – see if there's even any gap – as they closed right up on my MFI Carrera and it behaved like the fuel pump had packed up, ran roughly, backfired, you name it... Just a thought before getting too carried away.

Hi,

Stupid question but what is 'the points'?

chris68 · Post by **chris68** » Thu Apr 23, 2009 6:30 pm

Hi,
The points are a contact breaker that live inside the distributor. This cam operated switch interrupts primary current flow in the ignition coil causing a large secondary coil voltage and resulting spark at the spark plug. It's a bit different if you've got an electronic ignition but this description is valid for a conventional ignition circuit.

Hope that helps,
Chris

IanMcLeod · Post by **IanMcLeod** » Fri Apr 24, 2009 9:17 am

I have exactly the same symptoms at the moment. Halfway home after flooring it at the traffic lights cars started running like a dog and behaving this way. Sluggish, poping, etc. Could barely coax it home. No smoke so at least that is a good sign.

Points are fine and timing is bang on so will try fuel system next.

Ian.

ross.mcw · Post by **ross.mcw** » Fri Apr 24, 2009 10:14 am

Hi Mike,

Great to hear you found a car! Your problems sound very similar to some that I had last year. I'm sure you've already checked this, but in my case, it was the distributor cap and rotor arm which were worn to buggery. Replaced them and it's been fine since then.

Any pics of your car anywhere - definitely interested to see what you found in the end.

Cheers, Ross.

Gary71 · Post by **Gary71** » Fri Apr 24, 2009 11:18 am

Hi,

My process of elimination for this one would be:

Ignition:
1. Points - Sounds like you've already done this one though.
2. Ignition timing - Is the vacuum pipe connected and functioning? Does the timing advance when you rev it?
3. Coil HT lead - Is it in good condition? Are the ends corroded?
4. Dissy cap - Are the contacts where the HT leads go in rotted? Are the contact s inside in good condition? Is the carbon brush in the middle worn out?
5. Rotor arm - Is it cracked / corroded?
6. Main HT leads.
7. Plugs

Fuel:
1. Fuel delivery - Take the feed pipe off and check you have a decent volume flowing
2. Clean the idle jets - Mounted on the side of the carb and easy to get to.
3. Check the throttle linkage is connected properly between the carbs with no slack and that they open and close together
4. Take the tops of the carbs off and check they are not full of muck.
5. Make sure the floats float! ...and turn the fuel of when they float.
6. Clean out all the jets, accelerator pumps, etc, i.e rebuild the carbs.

Hopefully it will be one of the simple ones like Ross mentioned, probably in the ignition system. A new cap, arm, plugs, HT leads and points never did any car any harm

Good luck

miles5 · Post by **miles5** » Fri Apr 24, 2009 11:47 am

Hi,

My process of elimination has ended up being - call Tuthills - what a jessie. These things just frustrate the hell out of me and I would rather not start chucking my tools around the garage.

In my defence I am only 6 miles away from Tuthills!!

God it looked god on the back of the trailer!!

Ross, pictures of the car can be found here
http://www.ddk-online.com/phpBB2/viewtopic.php?t=24699

Interesting thread and obviously not an uncommon frustration.

I will report back on the outcome.

Best,

Miles.