mgf

[markisgoing]

hi i have just had head gasket done and i am know getting high idling ie start car idles low then goes up to about 1500 revs have tryed usaual thing new throottle body checked connections sprayed sensors but sounds like air is sucking in any suggestions thanks

[MaddAussie]

This link may help
http://www.mgf.ultimatemg.com/group2/th ... /index.htm

[markisgoing]

hi tryed doing the things on website above but still the same any more suggestions

[Mykel]

Mark,

I had the same problems on my MY2000 VVC. Bought her form first owner in December, drove her home (350 miles) and she already had the hanging idle revs. Just after having arrived here, I had a HGF and everything was taken to pieces and refitted again. New belts, new water pump, new tensioner, emission test, throttle position sensor adjusted, name it - they did it.

The idling continued to be tricky. Sometimes with warm engine I had up to 2,300 rpm at the traffic lights, quite annoying. I tried the push-the-accelerator-five-times thing over and over again, sometimes it worked, but mostly it didn't.

But now I sorted it all out: Given the facts that (a) the previous owner was a retired gentleman who only drove some 2,000 miles a year and (b) me being very, very cautious after the HGF, the engine was hardly ever revved up properly. So I decided to push a bit harder for one tank filling, never revving over 3,000 when cold obviously but also not below 2,300, changing gear like a madman. As soon as the oil temp gauge reached 90 degrees (which apparently on a MY2000 is a lot less in reality) I went for up to 4,500 rpm, when hot (120 degrees gauge) pushing as hard as the winter tyres allowed.

To put it in a nutshell - she is behaving very properly by now, engine running smooth and responsive to throttle, no high revs ever again. I've been told that this treatment works out many a problem, especially on VVCs, but I don't know what model you have.

HTH
Mykel

[markisgoing]

hi i have a 1997 vvc been out today took air manifild of cleaned around again but now have a sqeakay fan belt when fan belt sqeauks it now idles funny when squeak there normal revs just now revs drop and go up just when first started thanks for your reply what your saying is drive it a couple of hundred miles

[adrianclifford]

Ah, the Italian tune-up

[Mykel]

... ma si, signore!

[Mykel]

Me and my big mouth again ...

Seems I simply shouldn't write or talk about solving issues any more. After everything about revving has been perfect for at least two months now, since yesterday things are getting worse again.

The engine starts quite well in the morning, yet after warming up the idle revs are most irritating. I've had everything from 850 to 2.000 rpm, but mostly the needle just hops around between 1.000 and 1.600, hardly ever taking a rest at one defined number. At the traffic lights people are already staring at me, as if I were a nervous young stronzo .

I also found that when starting the warm engine, it is not as responsive as when cold, actually it feels a bit as if one cylinder is missing. If the idle revs really go down to ~800 it also seems a bit rougher than normal, then the ECU spontaneously ups them to about 1.200 rpm. But when driving, everything is completely normal, no rev limiter kicking in, only fuel consumption seems a bit higher than normal, but you can never tell that for sure before a visit to the pump.

So I am afraid that this weekend won't see the DTLRs fitted but me hanging over the engine bay looking after the things in the following order:
- air filter (still the original model, last serviced 4 years and 11.000 miles ago)
- clean the wires' connectors to sensors and ECU
- take off and clean the IACV
- ignition cables and spark plugs (never changed within 11 years and 37.000 miles)

Fortunately I have a complete service history (including all the garage's invoices), so I do know what has been (or rather: hasn't been) done in the past.

Any other idea? All suggestions are warmly appreciated.

Cheers
Mykel

[Rob Bell]

I think that's a good start Mykel. Check the throttle body plug, loom wires and connection. IACV can sometime cause problems like this - but I think that HT cables is more likely to cause problems with uneven running rather than a fast idle? To be honest, this could be the good old fashioned problem of the ECU water temperature sensor...?

[Mykel]

After a terrible ride in the morning (revs up to 2.800 rpm idle, no joke!) I'm back from the yard and found some rather interesting things under the engine cover

First one ... the air filter. Please keep in mind that the head gasket was changed in December plus some other bits and pieces replaced (belts, water pump, tensioner ... the usual stuff) for some 1.700 Euros. I had some problems afterwards already with the alternator belt, so Lilibet had to visit the garage twice again. Yet it seems none of the staff had noticed that all four airbox clamps were open. Not just wrongly attached ... completely open and loosely hanging around, leaving the air filter completely useless. Great job done there. Panel filter obviously wants to be replaced, couldn't get one today, so I just vacuumed it for a start.

Next, the HT leads. I took some pics (sorry, iPhone only this time) showing serious burns around the cam cover bolts:

IMG_0085.JPG (84.47 KiB) Viewed 1572 times

This applies to all three cables running along the bolts, and I couldn't check for more burns along the line to the coils. So these are definitely rotten and cry for replacement. Garage guys also didn't notice this some 3.000 miles ago when the head was off. Might as well explain the rough run of the engine. As a first aid measure, I simply taped them:

IMG_0087.JPG (113.4 KiB) Viewed 1572 times

But this won't really help of course.

Next go was at the IACV, which looked horrific:

IMG_0088.JPG (68.54 KiB) Viewed 1572 times

I gave the little fellow a good brush-off using contact cleaner and then lubricated it with a little bit of WD40. The counterpart was also cleaned of course.

All connectors were taken off and together with their respective sockets I drained them with contact cleaner. I also took the opportunity to measure the resistance value of the water temperature sensor. I did this twice, first when the engine was cold (or rather so, as I had to use the car in the morning), reading on my stone-age analogue multimeter was some 1.2 kohms at ~35 degrees. I then reconnected everything and ran the engine until the water temp gauge was at normal operating temperature. Reading went down to approx 250 ohms. From what I know, these values are well within tolerances. Also I've never had problems with the radiator fan, so I would actually rule out the sensor.

After refitting all parts, I went for a short test drive (10 miles or so). Halfway, when the oil temp gauge was also normal, I stopped, turned the ignition off and performed a stepper motor reset. Afterwards everything seemed to be alright, yet occasionally the revs were still stuck at 1.400 but back to normal when returning home.

From all this I draw the conclusion that the faulty HT leads cause dropped sparks and therefore the ECU has to rev up a bit sometimes as to not let the engine fail out completely. This might also explain the rather low mpg I achieve, never got better than 37 even when the right foot is not so hot tempered.

So I will now opt for some Magnecors, new NGK platinum plugs and a new air filter panel of course. This should cure the disease, shouldn't it?

[Mykel]

Just another HT lead burn example (only 3 attachments allowed per post):

IMG_0086.JPG (90.94 KiB) Viewed 1572 times

[markisgoing]

hi i have a split in number 2/3 would this cause the revs to not idle properly then thanks

[Mykel]

Will be some days before I get the new leads and plugs. I will then post the results here of course.

[Rob Bell]

Well, the HT leads definitely needs replacing - no shadow of a doubt. Whether you invest in Magecore or just use standard repalcements? I'm not sure that there is much of an advantage to the Magecore items, but then that said, I have had Magecore HT leads on my car for over 10 years now, and ever a problem... so they're good quality, and certainly worth considering.

Mykel, may I move this thread to Technical?

[Mykel]

Rob, from my side it's okay to move it, yet I am not the thread opener. If Mark is fine with that ...

I think I will go the Magnecor way, it's 60 Euros vs. 87 Euros as to the current offers I got, that is okay. What do you reckon air-filter-wise? Does it make sense to get a K&N panel filter for 50 EUR rather than the standard paper model for 15 EUR instead?

Cheers
Mykel

[Rob Bell]

Hopefully Mark won't mind - I'll leave the reminder here.

[markisgoing]

hi no idont mind carry on thanks for the replies

[Mykel]

As I didn't find any reasonable offers for Magnecor leads I had to go a different way with that and fitted 8.5 mm double silicon ones I found on eBay, seem to be almost similar to KV85. And a set of NGK Iridium plugs.

The plugs were an easy fit BUT the leads ... I do know you Brits are world famous for being fond of pain, but the way the HT cables are fitted on a VVC leaves but one conclusion: this design was created by the chairman of the Longbridge local S&M club. They even remembered to put some cable ties right where your arm has to go, inevitably causing some neat scratching

But back to topic: After having done almost everything I can actually think of, the idle revs still seem to be a problem. The car's behaviour had improved a lot after I cleaned the IACV and all the connectors. Normally she starts well and the revs are stable at 800-850 rpm when warmed up. It became a little worse over the last days, but not as bad as before, just stuck at 1.400 occasionally.

After the plugs and HT leads were finally in place this morning, I went for another test drive. She started fine, running smoothly, idle revs and acceleration perfect after warming up as well. So I waited for the oil temp to reach 120 degrees (remember: MY2000, this means 90 degrees effectively ) and gave her a good rush, revving up to 6.500 full throttle. Next comes a village with a 20 mph speed limit, still everything okay.

On the last bit approaching home I stopped to perform a 0-60 test. Pretty nice, some 8 seconds or so, keeping the throttle down to 85 mpg in 3rd gear. Comes the traffic light, shifting down ... idle at 1.400 rpm again. Oh b***er says I ! Home is just 300 metres down the road, I park the car, she stays at 1.400 ... Engine off, starting again only reluctantly and still idling at 1.400 ... another three times, no improvement.

I then performed an IACV reset, she started a little better and after a brief jump the idle revs came down to 850 again. When I listen to the engine idling, it sounds a bit like someone is pulling a brake on it or rather like strangling it, don't know how to describe it. Its not as if the revs are changing, but the sound is a bit awkward, almost rhythmic.

The only thing I haven't changed yet is the air filter. But what really puzzles me is that she runs well when reasonably warm, yet when hot the problems get worse.

Any further ideas anyone ... please

[redarrow]

I am guessing, I was told if the oxygen sensor is bent, or offset you get high revs,don't no if that helps,

Also was told that, when the coil pack get warm, then hot all problems start, even high revs.

Also there the throttle to cheek, and then the pedal it self, could be a sticking problem.

Maybe throttle cable sticking.

The worst i would hate and scares me, i read a problem like this, and it was the (ecu) that scary. ( a internal component went , computer frayed, told the revs to rev high)).

I would cheek the throttle cable for sticking, they say you can release this via pushing throttle 5 times hard.(accelerator pedal to others.

Please cheek the oxygen sensor is not bent, i no not some think easy to get to,just undo the two back heat plates, undo the nuts on the engine block push manifold forward, then inspect.(a new one will be good idea.

Then there the cat another thing to give high revs.

you say it eating petrol, replace cat and oxygen sensor(better fuel consumption in general)

good luck.

that all i no about high revs.

I don't think a air filter will do it, unless there a tree in there, blocking the whole hole.

When you inspected the throttle, was it ok, i have never been able to no via sight, if it gone or not, might look ok but is it.

To me, sounds like the oxygen censor got moved, and wrongly position while the manifold was taken off for the hgf (only my opinion.

[Mykel]

Hmmm, actually I was also worried about the cat and lambda sensor. Yet as the car flew through her TÜV (=MoT) in December with no issues at all, including emissions test, I didn't take this into account really. High idle has always been a problem with this one, the previous owner told me. So even before the test was carried out.

Any ECU problems would also have shown up during the emissions test as the car was hooked up to a Testbook environment and the TPS recalibrated.

I won't be going for a new cat right now as this will be part of another piece of work to come, which is fitting a 4-2-1 s/s downpipe together with a complete s/s exhaust system. But She Who Is In Command won't be happy with me spending that much right now