running problem on 1.2 nova someone must of had these symtoms before and can help

[nova_mike]

Please dont let the essay put you off!!


I have recently purchused a nova 1.2 c12nz 54,000 miles (good condition bodywork wise but lack of maintenance service wise) as a run around paid peanuts for it due to it having many mechanical problems which now are all cured apart from this one.

problem that is stumping me:

symptom
Upon starting the car from cold you find it will not start easily i.e. if you turn it over it will fire and just about tick over (very lumpy) jus going bop bop bop poof and then dies you have to hold the throttle wide open and keep it cranking until eventually the engine picks up revs flat out then back off and it will idle but quite high about 2200 rpm.

After it gets to operating temperature the revs die down and will idle around 950-1000rpm ish, but now if you apply throttle fast it hesitates around the 2000rpm range, splutters then pics up again and clears up the rev range.

Though if you were driving and did this e.g. pulling away from a yellow line as you build up the revs and go to drop the clutch, the slight hesitation and spluttering causes the engine to stall then your stuck in the middle of the road with the starting problem all over again explained above, trying to restart with cars beeping at me lol.

Work already carried out

New:

plugs
leads
dizzy cap
rotor arm
air filter
idle control valve
throttle position sensor
thermo switch (cts)
oxygen sensor
thermostat
oil + filter change
cylinder head removed - re lapped valves new stem seals decoked head refitted with gm head gasket, new head bolts an all new other gaskets too + new lifters, T belt an water pump.

have done compresion test and have good compresion accross all 4 cylinders

I have tried a working map sensor with no change.
When i put the new oxygen senor in the problems seem to go away then over the course of a day the slowly came back the more i used it.

It seems to be running rich/overfueling when i get the problems i'm finding it smells strongly of fuel, also lots of soot out the exhaust which i guess is sooting up the probe making the problem worse, cats working overtime and stinking of eggs. i'm also thinking that its fowling the plugs causing it to miss and splutter causing the difficult starting and hesitating during driving.

This is all i can think of to explain the situation.

My question is what should i try now?? or what can i do to find out what is causing it?? someone must of had this or a similar problem before!! any advice will be greatly appreciated!!

next line of attack injector ?? ecu?? want to solve this asap as its bugging me a lot lol


regards mike

[nova_saloon]

timing maybe still a little off, or just a nackered engine, and all that stuff must of cost you a bundle :(
check the compression
change the oil and oil filter because that isnt on your list.
fuel pump could be a little clogged
injectors may need doing,
try finding another ecu or borrow one from someone, but unlikely
check all sensors even replace them all.
the list could go on unfortunatly

[nova_mike]

thanks for your reply mate,

sorry forgot to put that in will update list now, i have done oil and filter and done a compression test too which was why i did the head gasket as it was leaking, but now all cylinders have good compresion the motor has only done 54k too so its not in overall bad condition.

also i did the timing with a strobe at work an its spot on, as for engine timing thats spot on too.

regarding sensors not really any left unless i got a duff new one hmm

thats why im thinking injector or ecu although i agree it is very unlikely.

it has cost a few quid spent around £300 not all gm stuff few ebay specials lol

mike

[AlexW]

It could be the ECU but tbh it sounds more like sensors than anything.

a 1.2i ecu is easy enough to come by and are always dead cheap.

PM Cooltiger as i belive he still has his 1.2 ecu.

[rrv8]

Collapsed cat

[Adam]

These engines rarely go wrong, but when they do its usually a coil/dizzy problem.

Try another dizzy and coil(the dizzy tells the ecu the engines rotating..) so if its got an intermittent fault you will get misfires/hesitation.
Same if the coils overheating and giving an intermittent weak spark

[mowgli]

Collapsed cat

its worth a look, drop the exhaust off at the joint under the sump & try it..

have you put anything like redex through the fuel system? or changed the fuel filter?

[AlexW]

Have you flashed out the codes though? Just thought about it as its 1.2i

[johnny_turbo]

i had the same problem with mine it turned out to be the inlet manifold gasket was gone

[nova_mike]

hi all thanks for your replys

i will be trying all of the above sugestions and report back!

have not flushed redex or anything through, nor have i flashed out the codes how do you do it mate? defo worth a go. which pin's is it?

dont think its the inlet gasket as it did not cure the problem after i did the headgasket as changed the inlet too thanks though

will try get another dizzy as that is a good direction to head in also will drop the downpipe off tomorrow and try running it as it doesnt cost anything to do a simple check

thanks again for all the advice:thumb:

mike

[bmw156]

i was gonna say the coil, might be braking down, under pressure.

[nova_mike]

i was gonna say the coil, might be braking down, under pressure.

good stuff will be trying this too mate cheers

mike

[AlexW]

Doubt its the coil...

To flash the codes, turn off the IGN and then get a paper clip or a bit of wire and bridge the bottom two pins on the diag plug (if the holding clip is at the top of the plug) check it tho as i cant remember off teh top of my head. Should bridge the earth and eather brown/yellow or brown/white.

EDIT: Only told you half lol, turn on the IGN and the ecu light will flash 12 3 times and then flash another 2 numbers 3 times usualy. Then it should go onto the next code untill it comes up with 12 again.

Its like one flash, pause, then 2 flashs means 12. And so on.

Should tell you if the ecu has any fault codes stored.

[nova_mike]

Doubt its the coil...

To flash the codes, turn off the IGN and then get a paper clip or a bit of wire and bridge the bottom two pins on the diag plug (if the holding clip is at the top of the plug) check it tho as i cant remember off teh top of my head. Should bridge the earth and eather brown/yellow or brown/white.

EDIT: Only told you half lol, turn on the IGN and the ecu light will flash 12 3 times and then flash another 2 numbers 3 times usualy. Then it should go onto the next code untill it comes up with 12 again.

Its like one flash, pause, then 2 flashs means 12. And so on.

Should tell you if the ecu has any fault codes stored.

ah bargin sounds pretty simple will check it when get home in about an hour, there should be a couple stored as i have had the warning light come on a few times fingers crossed

will let you know tomorrow cheers mate:thumb:

[nova_mike]

Hi mate

got home last night and flashed out the codes but all i got was 12 over and over so guess thats no help, yet i have had the engine light come on before hmm thinking about it, it was before i changed the probe that happened so maybe the new probe is not carbon'ed up enough to regester a problem yet i have no dought it will do eventually again if i keep running it. i have sorced another injector which i dont think is going to make the differance but worth a try so will try that tomorrow, and have sorced another (working) dizzy off here so will update once fitted it. im still sure its down to overfueling but dont understand why it would? if changed all the sensors that the ecu collects its data from and no engine faults, will carry on the investigation tommorow.

[AlexW]

How many times did it flash 12?

[nova_mike]

i let it flash 12, 4 times all together i will run it tomorrow and try again when get to work as i havent used it for over a week now. may bring up a fault.

[AlexW]

Hmm if it was 12 4 times then it seems like there was no fault code. It should flash 3 times and then flash the fault code.

Run it and see if you can get the light to come on and see what happens.

[nova_mike]

Right spent an hour on the car tonight,

swapped injector as had another one and would not run properly, put old one back and the same.

took plugs out all four covered in petrol, so gave them all a quick clean and tried for spark, all 4 had strong spark. popped them back in and ran (lumpy as fook) then pop pop bang stall. took plugs out and dripping with fuel again, cleaned them, put them back in ran again same as above.

flashed for faults and go 12 12 12 12 ect... so nothing there tried wit exhaust off and no differance there either.

not leaving many things left to try lol kind of got my hopes up on the dizzy causing timing to be out, would explain all the problems.

mike

[mowgli]

did you try running it without the exhaust on??
has it had the lambda sensor checked?

[nova_mike]

did you try running it without the exhaust on??
has it had the lambda sensor checked?

yes mate i only dropped it off from the manifold then after made no differance connected back up. i have fitted a new probe last week still no luck with it.

[Guderian]

Sorry to thread dredge on a 9 month old Nova gremlin, but.... I have EXACTLY the same symptoms on a 1.2, am just wondering if it got cured, and if anyone has any alternative explanations.

My favourite theory is a poor connection in the low tension system somewhere (probably at a connector) or a chafed wire.

The reason i say this is i was under the bonnet doing sundry other things last night and i appear to have jogged something and actually made it worse..

Just off now to take the multi pin off the distributor and see if it is full of green.

[Annie]

Had this problem on my 1.2i, we changed every thing. turned out it had jumped a tooth on the cambelt before we bought it & the someone had messed with the dizzy to try & hide it. I've also had a problem showing the same faults as above, changed the lambda sensor but turned out the wire had broken up inside. worth a check using a multi meter. :)

[Guderian]

Many thanks, i THINK i have cured it-- With the 'glove trays' removed, the plastic trims can be removed from the inside of the 'A' posts. This reveals an innocent looking brown earth wire on both sides. Both were loose and one was green with corrosion. Checked the behaviour of the car with the wires disconnected and it turns out that both wires are critical and the engine won't run without them (remember this is a late model 1.2spi with ECU.)

The ring tags are brass so i just cleaned them up and copper greased them. Then drilled new 4mm holes for the earths slightly lower down on the 'a' post, rubbed down to bare steel, greased and reconnected.

The engine still ran like a dog but only until i had driven a few miles-- it turns out the adaptive part of the ECU had lost it's memory when i took the wires off, and needed to re-learn the idiosyncrasies of this particular engine. During this learning period the idle was all over the shop and the engine was surging.

Now it's happy.