Rough running

[Rissy]

Hey folks,

I've finished getting my car back together again after an arduous 7 week constant period of work to it.

Amongst my work, I changed my old fuel lines for new ones at the tank and engine (except I'm still running original fuel feed from the filter to the fuel distributor cause I couldn't get access to the filter without ramps, so
I'll leave that one until I'm back in Edinburgh - could probably do with a check for fuel filter model required these days too?)

Anyway, I started the car up for the first time on Sunday night. It took nearly 10 mins of almost constant cranking to get the thing to start and then about 20 mins to settle down to the point it's constantly at now. I ran the engine again last night. In fact I also risked a short drive to get fresh fuel put in the tank.

However, the engine is still running really rough compared to normal.

The car is hesitant under acceleration. I really need to push the pedal down to overcome the hesitation, and the engine idles more rough than usual. The engine sounds more growly than normal. Less smooth. It's more smelly now too. Almost like I'm running rich.

I've checked the seating of all the injectors and plugs. They're all good. I don't suspect the engine to be misfiring or running on fewer than all 6 cylinders because the engine isn't rocking like it was for that first 20 mins on Sunday night. It's idling at just below the 1000rpm mark.

I've had it suggested to me that it might be a vacuum leak. I'll be pouring all over the engine tonight to check for anything obvious, but I was very careful and methodical at rebuilding the top end of the engine since I was also in to the VOD a few weeks ago. I've got all new o rings put in upon rebuilding too.

Does anyone have any other ideas if I can't find any vacuum pipes damaged or loose or pulled off etc?

How do I look at adjusting the air/fuel mixture if this might be necessary?

I can probably get the 2.5hrs to Norfolk like this, but it ain't gonna be easy going. Id appreciate some helpful feedback from anyone willing to help me. If it's easier to talk me through anything on the phone, my number is 07717454140. I'm all ears and in need of an expert friend. Thanks.

[Chris Williams]

I still think it's 'probably' something simple like a vacuum leak somewhere, either that or something is still not quiet right with the fuel system. Other than a methodical check of what you have done the other good way to check for leaks is using a can of WD40 spraying this around all the possible areas you have disturbed whilst the engine is running this should pull it in and burn through the engine then you know. Being as how it also took so long to actually get the engine running whilst I was on the phone it could be a lack of fuel from an injector. Again fairly easy to check as I'm sure you know. Pull the injectors and place them in little jars, pressurise the fuel system and push down on the plate as I explained the other night. You will get a good idea then if your getting a good supply of fuel through to all the injectors.
https://www.youtube.com/watch?v=V1adoUkH70c
Chris

[Rissy]

When you do that test, do all the injectors not spray fuel at once?

He's doing them one at a time...?

[Rissy]

Ah wait. I can see in one shot, the fuel coming out at the same time on another in the background.

I'll trying pouring all over the engine tonight and see what I can see.

[Chris Williams]

Yep, as you noted ideally six little jars :wink:
Chris

[Rissy]

So, just quickly to keep people abreast of what I've done.
I've pulled each spark plug cable one by one. The engine is rocking anyway, so it's difficult to determine if doing this causes the engine rock more or not. I think so. The air intake Venturi diaphragm gasped each time I removed a plug though (whatever that means)

I've sprayed wd40 around the bull horns, the square sections of the antlers and where each of the 6 intakes of the antlers meet the engine block. Each time there was no reaction from the engine.
The pipe of pain shows no sign of shining light eking in around the seal into the metering body when looked down inside.

I've checked the state of the gauze inside my CPR. Apparently looks ok.
Ivenot pulled any injectors as I don't have any receptacles to contain any fuel. When I push down the Venturi intake and I can hear petrol squish down in the cylinders, Although not aware how many, of course.

I've looked at this tuning screw inside the metering unit. It's almost screwed right down. There's about 0.5-1 threads worth sticking out of the plate it's screws into. It seems to be a 2.5mm hex key head. I've got a long set of Allen keys on order from screw fix which I should be able to collect after work tonight. My shorter one fitted into it, but I wouldn't be able to turn it due to the "L" shape nature of the thing.

I've been into the VOD, and rebuilt and along the way, changed the fuel lines while I was at it. When I last ran the engine last, before doing any changes to the engine, the engine was running sweet as a nut. As always. No problems at all. That was 7 weeks ago.

[Chris Williams]

I still think (as per post's on facebook) that you should not be pulling things apart/adjusting things until you can 100% rule out what you have done so far. One of the biggest failures we have ( and I most certinally include myself in this) is ruling out something because it's new. Your car ran fine before you took everything apart, you have not touched the ignition side so should be ok, but should be easy to check. Your car was VERY difficult to start when it came to getting it started after you finished all your work (20mins) and then ran really really roughly for nearly 5 mins. I would still check the fuelling before going anywhere else. It may be something as simple as a piece of swarf left in an injection hose. And I'm not having a 'go' at any ones parts just suggesting it 'might'
Can you drive it over to me (on route) Friday to help if you have not got it sorted?
Chris

[Rissy]

I'm guilty of not blowing through the hoses or anything, I'll admit.

I would hope there would be some quality control carried out at manufacture though.

Each hose came capped off at each end.

I only removed these caps in order to fit to fuel metering or injectors.

Injectors were only out of engine for max of 5 mins each. In a clean environment, to attach to fuel lines which were plugged up until the point of connection to either the injectors at one end or the fuel metering at the other. Nothing was left open or lying around, and most certainly everything was done in a clean atmosphere and surroundings.

As for getting to you. I'm not sure how many more miles that will add to the journey, but I will be carrying a load of tools with me to Norfolk if that helps. I just don't have any specialist equipment like fuel pressure measurement or gas measurement etc.

I still don't know how the car will handle on its way to Norfolk as I've not had a wheel alignment done at all!

I'm totally exasperated and scunnered now.

[Chris Williams]

To be fair your probably right, I'm sure there is nothing at all wrong with them (hoses) however it's best to check everything regardless of it being new or old!
If you wish to stop over on route that's fine I'm around all day Friday and have a new set of plug leads (will bring them to Norfolk just in case) It will only add about 5-10 miles to your trip as I'm on route for you. If we cant get it right then I'm sure Rich will be more than happy to have a look at it and sort it for you
Chris

[Chris P]

Just my 2p…I agree with Chris W….its probably something you have inadvertently done.

i'd be very reluctant to 'adjust anything'…things don't go out of adjustment on there own and when you have 2 faults you have BIG problems!

What spark plugs have you got in? Did you change them? Have you checked the gap? I made this mistake in the last couple of weeks!! All sorted now.

[bjbrownie]

It might not be this, have you checked the ballast resistor connections-it's possible to knock these while you're working around the back of the engine-it's easy to do and it could be a loose connection there.

[stunned_monkey]

Leave the mixture screw alone. A quarter of a turn means the difference between a running engine and a not running engine. Or a running engine and a badly running/rich engine if going the other way.

[Rissy]

So just to close out this thread (at least for now).

I did an injector test last night. I didn't push the diaphragm all the way for this test, but kept it at a constant position, relative to about double the opening distance as that expected at idle. All 6 jars were filled by the exact same amount.
While putting them all back, after being advised to pay more attention to my HT leads, that's exactly what I did. I removed all 6 spark plugs and looked at the condition of those and the spark plug ends of the leads. I only had one pretty decent looking lead. 4 were pretty bad and 1 was especially bad. Cylinder no. 4. The plug for that cylinder was completely coked up solid black. The others weren't brilliant, but a lot better than no. 4.

I cleaned them all up and tried to scrape down to better metal on the leads the best I could with a Stanley knife etc.

I put it all back together and it definitely made an improvement. It's still not perfect by any means, but at least the engine isn't jumping around as badly as it was.

I took the car for a high speed trial along a junction and back on the M6 after this. The car is completely drivable now, as long as things don't deteriorate again. It's a little jittery at higher speeds, the engine hiccups every so often and at lower speeds, especially in a higher gear, it's a bit hesitant.

I've got new HT leads, dizzy cap and rotor coming to me today. I'll bring them with me to Norfolk in case, or if anyone fancies a tech session...

So glad I completed all my work in the time I had (with one night spare to pump up tyres, give the car a wash, pack my bag and have a decent meal and an early night for the first time in 2 months)

I'm totally knackered.

[DMCTodayMichael]

Just read through this and the only thing that caught my eye was this. WD40 may not be the best thi g to check with. You might want to do the same test with carb cleaner. Although WD40 has some volitile properties, it's just a small amount used as a carrier.

I'm thinking 2 things. One is a leaking injector seal. Cheap and easy to replace, and easy to check with carb spray. If you do replace the seals go ahead and get six injector clips as well(I can never get those off without one or 2 bending).

The second is actually the mixture. Monkey was right in telling you not to mess with it. You need, every DeLorean owner needs a dwell meter. Anytime you change anything on the fuel system, you need to check your mixture adjustment. Easiest is a dwell meter, the most accurate is a O2 probe, but a dwell meter works just fine. Pick yourself one up for as little as 20 or 30 dollars.
You can not adjust the set screw without this, 1/8 of a turn is the difference between your car starting and not starting.
Again, I'm not saying to adjust your mixture, just check it

[stunned_monkey]

A dwell meter only works if you have a lambda system. Chris doesn't. I set the mixture originally using my CO meter.