An old nemesis has returned !
Discussion
Sadly this heck of an annoying problem of 'lumpy idle, misfiring & gradually cuts out' has returned.. It has happened twice on my driveway now with the car stationary & a few weeks ago it sounded like it backfired when i was out & about so i had to pull in very quickly! Struggled to start back up again but after leaving it a few minutes it did finally start & i was able to get home (thankfully)
So the car starts up first time with a lil bit of a rev but wont start with just a turn of the key (always been like this.) The revs do seem to keep rising once its started up, 1500rpm then fall down to idle at 1000, now it was around 1100rpm an 900rpm idle before so im not sure why it has suddenly increased.. (only thing that has been changed months ago was a severely cracked rubber hose from servo to plenum & the air filter to a k&n one, would this let more air in & possibly mess up the mixture? Please note it has been driven since & was totally fine untill past few weeks)
I cant actually get the car back to the auto electrician in Coventry who worked on it before, as it will most likely conk out at traffic lights/slow moving traffic & probably not start back up again leaving me stranded
so im abit stumped.
Last year it had new ht leads, spark plugs, fuel pump, ignition coil has been checked over & is fine. Tony at Coventry car centre repaired the air flow meter which was a state inside (plate had dropped plus split on actual rubber cap) & it was running fine as i done a good 80mile in it there & back a few times.
Alan461 kindly came over & took a look last winter, he pointed out points on distributor cap were green, corroded, so i ended up replacing that for a new one.
Another point to make it is kept outside with a breathable cover on, would moisture possibly be getting at some electrical ignition parts? I know it was kept inside at auto electricians & didn't conk out once for him (typical eh)
Anyone got any ideas? Im not as mechanically minded as the rest of you on here so please bare with me
Steve
So the car starts up first time with a lil bit of a rev but wont start with just a turn of the key (always been like this.) The revs do seem to keep rising once its started up, 1500rpm then fall down to idle at 1000, now it was around 1100rpm an 900rpm idle before so im not sure why it has suddenly increased.. (only thing that has been changed months ago was a severely cracked rubber hose from servo to plenum & the air filter to a k&n one, would this let more air in & possibly mess up the mixture? Please note it has been driven since & was totally fine untill past few weeks)
I cant actually get the car back to the auto electrician in Coventry who worked on it before, as it will most likely conk out at traffic lights/slow moving traffic & probably not start back up again leaving me stranded
so im abit stumped.Last year it had new ht leads, spark plugs, fuel pump, ignition coil has been checked over & is fine. Tony at Coventry car centre repaired the air flow meter which was a state inside (plate had dropped plus split on actual rubber cap) & it was running fine as i done a good 80mile in it there & back a few times.
Alan461 kindly came over & took a look last winter, he pointed out points on distributor cap were green, corroded, so i ended up replacing that for a new one.
Another point to make it is kept outside with a breathable cover on, would moisture possibly be getting at some electrical ignition parts? I know it was kept inside at auto electricians & didn't conk out once for him (typical eh)
Anyone got any ideas? Im not as mechanically minded as the rest of you on here so please bare with me
Steve
Edited by greyhulk on Wednesday 20th April 19:43
Top Gear TVR said:
If leaping to ideas if have gone for airflow meter or icv
Already had the airflow metre sorted out, the plate had dropped last time along with a split in the cap.. So I'm presuming that's all still working fine (I hope)ICV hmm this was mentioned before actually, where can I locate it? Not sure what exactly I'm looking for
Cheers
greyhulk said:
Le TVR said:
Is it lumpy idle while warming up or just when hot?
When warming up, literally start the car up leave it running, then when it idles gets lumpy an eventually cuts outWhat do the plugs look like when it has cut out?
mk1fan said:
It'll be that LED indicator relay.
Sorry, can't be any help on a 2.8.
Sorry, can't be any help on a 2.8.
that's been put on hold for nowLe TVR said:
I would start by looking for any possible air leaks on the intake side. Spray some EasyStart etc around the intake hoses and see if the engine reacts at all.
What do the plugs look like when it has cut out?
I replaced most of thecair intake rubber hoses with silicone few months ago, maybe ones worked loose? Or jubilee clip has possibly chafed oneWhat do the plugs look like when it has cut out?
Will take a look at the plugs when I get in from work, I did recall one looked a little white around the socket
I have a suggestion to isolate a trouble-spot - disconnect the warm-up regulator. This is just in front of the intake plenum IIRC and has two fuel lines running to it, a vacuum hose and an electrical connector. Disconnect and plug the vacuum hose - on my old 2.8 this made it run much better until I got the fuel pressures right. You can also disconnect the electrical connector if you like, but do it in a separate step to isolate that change. The electrical connector is simply for a coil that basically increases the control pressure as the engine warms up. The green relay provides power to this coil and the cold start injector BTW.
If you have to hit the throttle to get it started, the cold start injector may not be firing. You can remove it and carefully check to see if it sprays during cranking. It should only run briefly, based on the thermo-time switch.
It does sound a lot like you have an intake leak though if idle is high. Make sure that the small hoses are all nice and tight, or plug them for now and see what happens. The one going to the warm-up regulator is to improve throttle response only, so it won't hurt anything to run without it.
ETA - The 2.8 uses almost no electrical stuff to run, just a distributor and coil really. If it's running, they're fine.
If you have to hit the throttle to get it started, the cold start injector may not be firing. You can remove it and carefully check to see if it sprays during cranking. It should only run briefly, based on the thermo-time switch.
It does sound a lot like you have an intake leak though if idle is high. Make sure that the small hoses are all nice and tight, or plug them for now and see what happens. The one going to the warm-up regulator is to improve throttle response only, so it won't hurt anything to run without it.
ETA - The 2.8 uses almost no electrical stuff to run, just a distributor and coil really. If it's running, they're fine.
Edited by Loach1 on Thursday 21st April 17:37
Hi Loach1, I think the fact it dont start up witout some throttle is a issue i need to sort out, where can I locate the cold start injector is it the blue plug? (Sorry I'm useless with stuff like this)
I've just tightened up all the air intake hoses etc, used contact cleaner on a few electrical parts that were filthy.. Haven't checked inside the dizzy cap yet but as luck has it.. Its started up (with some throttle) & ticked over at around 13000rpm didn't seem to climb this time & idled at 1000-900rpm left it running for 15minutes, fan kicked in fine etc.. Hmm so all is well for now.. But i really want to sort this cold start injector thing out.
I've just tightened up all the air intake hoses etc, used contact cleaner on a few electrical parts that were filthy.. Haven't checked inside the dizzy cap yet but as luck has it.. Its started up (with some throttle) & ticked over at around 13000rpm didn't seem to climb this time & idled at 1000-900rpm left it running for 15minutes, fan kicked in fine etc.. Hmm so all is well for now.. But i really want to sort this cold start injector thing out.
Edited by greyhulk on Thursday 21st April 18:11
Yes, it's the blue plug. Thanks for the pic too - it reminded me that there is an intake air by-pass valve too, which is the piece that is at the front of the plenum with the intake hose routed through it. When the engine is hot I believe the valve should be closed, letting the idle drop to the base setting on the throttle body. You could pinch that hose to simulate the valve in the 'warm' condition. It also has a coil in it that should close the valve as the engine warms up. It gets power from the green relay too, so you could check there to see if the green relay is supplying power to anything.
Come to think of it, if you have a voltmeter or test light, check to see if the cold start injector is getting any power when you crank. If not, check the air by-pass valve for power when running. If neither have power, it could be the green relay or the fuse associated with the green relay.
David
Come to think of it, if you have a voltmeter or test light, check to see if the cold start injector is getting any power when you crank. If not, check the air by-pass valve for power when running. If neither have power, it could be the green relay or the fuse associated with the green relay.
David
Loach1 said:
Yes, it's the blue plug. Thanks for the pic too - it reminded me that there is an intake air by-pass valve too, which is the piece that is at the front of the plenum with the intake hose routed through it. When the engine is hot I believe the valve should be closed, letting the idle drop to the base setting on the throttle body. You could pinch that hose to simulate the valve in the 'warm' condition. It also has a coil in it that should close the valve as the engine warms up. It gets power from the green relay too, so you could check there to see if the green relay is supplying power to anything.
Come to think of it, if you have a voltmeter or test light, check to see if the cold start injector is getting any power when you crank. If not, check the air by-pass valve for power when running. If neither have power, it could be the green relay or the fuse associated with the green relay.
David
Cheers David, always find a pic easier sometimes Come to think of it, if you have a voltmeter or test light, check to see if the cold start injector is getting any power when you crank. If not, check the air by-pass valve for power when running. If neither have power, it could be the green relay or the fuse associated with the green relay.
David
, ive used some contact cleaner on the green relay it was covered in crap as was the cold start injector plug along with the black plug, red plug around the plenum.I haven't got a voltmeter but ill have to pick one up, if the cold start injector wasn't getting any power at all would this stop the car starting up completely tho?
I did notice the PCV valve/hose doesn't look in great condition looks like its cracked abit, not sure whether this would interfere with anything?
The car should be able to start without the injector, but it might take a few more turns. The injector doesn't fire for very long, maybe not at all, when the engine is hot.
Do you hear the fuel pump run for a second after turning the ignition on? I had a car that liked me to run the pump 3-4 times before turning it over so that the pressure was already built up in the system. A failed accumulator (next to the fuel pump) can cause system pressure to drop to zero when the engine is off.
The PCV hose could be a source of vacuum leak, so I would check carefully and temporarily plug if in doubt.
Do you hear the fuel pump run for a second after turning the ignition on? I had a car that liked me to run the pump 3-4 times before turning it over so that the pressure was already built up in the system. A failed accumulator (next to the fuel pump) can cause system pressure to drop to zero when the engine is off.
The PCV hose could be a source of vacuum leak, so I would check carefully and temporarily plug if in doubt.
The car should be able to start without the injector, but it might take a few more turns. The injector doesn't fire for very long, maybe not at all, when the engine is hot.
Do you hear the fuel pump run for a second after turning the ignition on? I had a car that liked me to run the pump 3-4 times before turning it over so that the pressure was already built up in the system. A failed accumulator (next to the fuel pump) can cause system pressure to drop to zero when the engine is off.
The PCV hose could be a source of vacuum leak, so I would check carefully and temporarily plug if in doubt.
Do you hear the fuel pump run for a second after turning the ignition on? I had a car that liked me to run the pump 3-4 times before turning it over so that the pressure was already built up in the system. A failed accumulator (next to the fuel pump) can cause system pressure to drop to zero when the engine is off.
The PCV hose could be a source of vacuum leak, so I would check carefully and temporarily plug if in doubt.
Hmm this might be why it doesn't start without revs then, I'll listen out for the fuel pump next time I start it up.
As I say it is working fine now but for how long I don't know.. Still think something isn't making it run as smooth
Its gone dark here now but I'll take a snap tomorrow after work, did you mean the rubber air flow metre cap?
As I say it is working fine now but for how long I don't know.. Still think something isn't making it run as smooth
Its gone dark here now but I'll take a snap tomorrow after work, did you mean the rubber air flow metre cap?
greyhulk said:
did you mean the rubber air flow metre cap?
Sort of, right next to the rubber cap is the fuel metering unit with spaghetti all over it. The top should have the 6 injector hoses and in the middle of them should be another hose that goes to the warm-up regulator. That is know as the control pressure and varies depending on engine temperature to change the air/fuel ratio. I don't see a shiny banjo bolt head in the center of the unit, but maybe there's a black banjo bolt that isn't visible in the picture. It's possible that someone has installed a metering unit without provision for mixture changes, which might be the cause of your rough running - it's rich enough for cold running but over-rich when running at operating temp.
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