Car popping on tick over and cutting out when hot

[halflife]

My car is popping on tick over and then when you have been driving for a while it will sometimes cut out when the you dip the clutch.

spent 30 mins tonight making sure the cooling system was properly bled but still popping. could anyone point me in the right direction of what i should look for next?

thanks in advance

halflife

[un1eash]

Is it firing on all cylinders? check all the plugs and make sure your getting spark on them all.

Then check the timing, also take the dizzy cap off and check for damage or moisture in the cap.

[mr2mk1chick]

check the timig and vaccume hoses, plus what is the normal idle speed of yours when cold versus hot?

[halflife]

thanks for the advice, I will read up on checking the timing. someone else had mentioned checking the dizzy cap so will take that off this weekend and have a look as well

When cold tick over is just uder 2,000rpm and then when hot 800-900

[un1eash]

It may not be firing on all 4 and another way to check is to pull the spark leads off one by one with the engine running. If theres no change in the engine tone or running then you know that cylinder isnt firing right.

[halflife]

It may not be firing on all 4 and another way to check is to pull the spark leads off one by one with the engine running. If there’s no change in the engine tone or running then you know that cylinder isn’t firing right.

It rev's fine and pulls strong, problem just seems to be on tick over, saying that though if i set the engine rev's to say 3K (using linkage in engine bay) you can still here her popping a bit (just don’t notice when accelerating).

Plan on taking dizzy off this weekend, inspecting plugs and if i can find a spare set swapping plug leads just to eliminate them

[BIGBOBO]

Have had the same problem for ages.

Checked vacuum leaks, ignition timing, valves, compression, ....
Replaced spark plugs, leads, distributor cap & rotor, cam belt, all filters,....

Finally noticed that the reistance on my ignition coil is out of spec (1.2 ohm where max 0,7 is allowed) so I bought a second hand coilpack on ebay.

Waiting for it to arrive, hope that'll fix it.

[halflife]

Have had the same problem for ages.

Checked vacuum leaks, ignition timing, valves, compression, ....
Replaced spark plugs, leads, distributor cap & rotor, cam belt, all filters,....

Finally noticed that the reistance on my ignition coil is out of spec (1.2 ohm where max 0,7 is allowed) so I bought a second hand coilpack on ebay.

Waiting for it to arrive, hope that'll fix it.

Thanks for that, another thing I can check at the weekend

[mr2mk1chick]

Sometimes when the TPS is faulty the tickover is poor when hot, but the popping (if its lke a backfire-ish) is often due to advanced timing. the dizzy may just need a tweak to retard it a bit.

[JMR_AW11]

Have you checked the mixture screw?


See
http://www.jmrhzu.btinternet.co.uk/mk1_ECU/part4p1.html

for some stuff about how it operates on a late model mk1b.

[halflife]

Update

Checked dizzy cap, rotor etc all seem fine (gave everything a good clean down anyway)
Tried mixture screw, made no difference so put back to where it was originally
Then started to fiddle with timing. If I retard timing sufficiently I can get rid of the popping but I loose power.

This has got me thinking. The car is fitted with a DTW tuned engine, one of the modifications (an £800 mod 7 years ago ) was to have the ECU rechipped and mapped. I am wondering if it has been set up to run on only the expensive stuff (98 RON). Unfortunately (and unusually) I have a full tank of the 'cheap' stuff in there at the moment so it will be a while until I can find out.

[BIGBOBO]

No luck on my part either.

Swapped over the second hand ignition coil pack - no difference
Tried the mixture screw - no difference
Unplugged every sensor - no difference

My bet is still on a vacuum leak in the intake or something with the fuel pressure at low rpm.

Oh, the original owner's manual suggests 98 fuel for cars without cat and 95 for cars with one, but as far as I know , no mk1 has a cat in europe.

[halflife]

Have you tried loosening off the dizzy and retarding the ignition a little?

[BIGBOBO]

Have you tried loosening off the dizzy and retarding the ignition a little?

Will try tomorrow but used a timing light to set it correctly couple of weeks ago, so don't think it will help.

The engine also hesitates a bit when pressing/releasing the throttle it seems (pointed out by a friend).

[mr2mk1chick]

Update

Checked dizzy cap, rotor etc all seem fine (gave everything a good clean down anyway)
Tried mixture screw, made no difference so put back to where it was originally
Then started to fiddle with timing. If I retard timing sufficiently I can get rid of the popping but I loose power.

This has got me thinking. The car is fitted with a DTW tuned engine, one of the modifications (an £800 mod 7 years ago ) was to have the ECU rechipped and mapped. I am wondering if it has been set up to run on only the expensive stuff (98 RON). Unfortunately (and unusually) I have a full tank of the 'cheap' stuff in there at the moment so it will be a while until I can find out.

If it was tuned up for fuel/air at the advanced timing then it wont be right when you retard the timing i don't think - hence loss of power.
I don't know enough about mapping to suggest how to remedy it apart from getting it checked or remapped.

[crazybrightman]

i take it you have an uprated engine and ecu? if so then the ignition timing may need stting differently. timing it to stnadard spec maybe wrong. how ever nearly all mr2's seem to miss slightly when free reving so i wouldn't worry about that too much.
if its been worked on alot internaly then they may have raised the c/r alot so high octane maybe required to stop knock but unlikely as they are quite a low c/r to start with.
have you tried adjusting the idle screw on the tb to up the idle speed say 50rpm as that usualy helps no end.

[BIGBOBO]

Quick question:

Is it normal for the mixture screw to turn more than 360 degrees?

Reading the article I get the impression it should only be 180 degrees.

[mr2mk1chick]

i take it you have an uprated engine and ecu? if so then the ignition timing may need stting differently. timing it to stnadard spec maybe wrong. how ever nearly all mr2's seem to miss slightly when free reving so i wouldn't worry about that too much.
if its been worked on alot internaly then they may have raised the c/r alot so high octane maybe required to stop knock but unlikely as they are quite a low c/r to start with.
have you tried adjusting the idle screw on the tb to up the idle speed say 50rpm as that usualy helps no end.

If there are different cams then the timing will be different.
backfiring is not good if its doing that, but a different 'lumpy' sounding idle is sometimes the norm for cams etc...

[halflife]

modifications include. Lightening and ballancing. Cams, porting and flowed. Ecu re mapped, 4 branch manifold and probably some other stuff i forgot. Machanic friend of mine has suggested that it might be supposed to run like that but i am not 100% convinced. Will try some higher octane fuel shortly and report back.

[BIGBOBO]

I think my distributor might be at the ends of it life.

Reading through the repair manual I noticed you should measure some gaps with a feeler gauge on the inside. They control the ignition so if the gaps are out of spec it will mis sparks.

Gonna check it tomorrow and report back.