Q4 igniton cut

axaQ4 · 06-07-07, 22:40

Hi!

I have a certain problem with my Q4

When i step on the throttle hard the car feels like the ignition is being cut(the car quit pulling for a sec) and there are "bangs"from the exhaust.It's very disturbing becouse i cant enjoy the car at its best.The most cut and bangs happens in 3. 4. and 5. gear thats the tricky part....i guess if the cables were bad this would happen in all gear....am i wrong?

I've already changed the igniton coils(or something like that...those 2 things
on which the spark plug cables are attached on....i'm not sure if coils is the right english term so i rather wrote a description

)

My next step is to change the spark plug cables i guess....

**Steve Webb** · 06-07-07, 23:16

Hi Axa, yep 'coil pack' is the correct term for the bits you replaced. As for your problem, are you running a non standard turbo or have you modified the engine much. Also which spark plugs are you using and when did you last change them?
And, does this problem happen at all revs or just at a certain point 2500-3000rpm?

I had a similar problem after having a hybrid turbo & manifold fitted. Standard spark plugs were not up to the job when the turbo came on boost. Giving the mis-fire type symptom that you discribe.
Also have you checked your fuel pressure recently? Running very lean could cause this problem.
Or if you have a split in the hose going to the MAP sensor, engine making boost, but the ECU seeing a reduced boost level and not proviing enough fuel.

Steve

axaQ4 · 06-07-07, 23:27

Hi!

I have the original T3 turbo.The mods i have are forged pistons, camshafts(fiat tipo 16v),polished exhaust canals,metal head gasket,hormann chip(around 240bhp) and a sport filter

.I have also raised fuel pressure according to the chip.
This happens only when i step harder on th throttle from low rpms. Mostly in the 3. 4. or 5. gear.the funny parts is that i can step on the gas in the 1. gear and the car goeas fine.

Where can i find the map sensor?

155'Ringman · 06-07-07, 23:53

Could be that the increased fuel pressure is giving you an over rich mixture causing the backfires.

**Steve Webb** · 07-07-07, 07:36

Here is where the Map sensor is. The connections come into it from underneath. Abit fiddly to get at, but worth checking that all the hoses are in order.

The reason why you might not get the problem in 1st and 2nd gear is that the ECU is programed to restrict boost in these gears. I'm not sure but I think the overboost function is disabled in these gears.

If the car was overfueling then I'd expect to see your problem in all gears. But if the car is underfueling for whatever reason, then it would be worst in 3rd/4th/5th because of the increased boost.

One question, did this problem happen after you had something done to the car, or did it just start happening one day?

Also you might want to remove a sparkplug or 2 to check on their condition.

Steve

axaQ42 · 07-07-07, 16:02

Hi!

I've checked the map sensor tubes and are all fine.But i tested it this morning
and i noticed that the ignition cuts when the boost goes over 1.25 bar....so this means that the computer cuts it.Look like the hormann chip doesnt handle this.I thnik this is my answer(i also got an advice from wolf66).

Steve i very much appreciate your help and thanks for your advices.I sincerly hope this is the cause of my problem.

Wolf66 · 10-07-07, 23:51

Originally Posted by Steve Webb

The reason why you might not get the problem in 1st and 2nd gear is that the ECU is programed to restrict boost in these gears. I'm not sure but I think the overboost function is disabled in these gears.

Steve

ECU does not restrict boost in 1st and 2nd gear. Turbo can't produce such high boost in these two gears, because it has no time for that. ECU controls boost only for certain RPM and load/TPS angle.

**Steve Webb** · 11-07-07, 12:42

Originally Posted by Wolf66

Originally Posted by Steve Webb

The reason why you might not get the problem in 1st and 2nd gear is that the ECU is programed to restrict boost in these gears. I'm not sure but I think the overboost function is disabled in these gears.

Steve

ECU does not restrict boost in 1st and 2nd gear. Turbo can't produce such high boost in these two gears, because it has no time for that. ECU controls boost only for certain RPM and load/TPS angle.

Sorry, I was just quoting what various 'grale specialists had told me in the past. But it does make sense that it doesn't control boost in 1st & 2nd as there is no way for the ECU to know which gear you are in.

How long does a standard turbo take to fully spool up then? Surely it can't be longer than a couple of seconds?

Steve

TangoQ4 · 11-07-07, 14:00

I've had the exact same problem.

I have the std Garret T3 and K&N sport filter. The symptoms started all of a sudden. At first, only in 3rd, 4th and 5th gears, but then it began to occur also in 2nd. I changed the spark plugs and seemed to go away for a little while, but then it started again. also checked fuel pressure coming from the pump and changed the fuel filter, but nothing changed...

Now, after some time having this problem and being unable to solve it, I found that the dump valve isn't working anymore (didn't have the time to inspect it yet, but I don't hear the tipical "ppssshhhh" when releasing the pedal) and turbo pressure has apparently decreased quite a lot (wasn't able to measure this either, but it's notorius how it doesn't push you back anymore after going over 3000 rpm's...

Could this lack of pressure be due to the broken dump valve??

Stuntz · 11-07-07, 14:04

CPU can know in wich gear you are in from the RPM and how fast you are traveling. But i dont know if this is the case in Q4 CPU. Will dig my head in this CPU during the winter.

Wolf66 · 11-07-07, 14:11

Originally Posted by Steve Webb

How long does a standard turbo take to fully spool up then? Surely it can't be longer than a couple of seconds?

Steve

If you disconnect the hose from the wastegate actuator, then boost will raise over 1 bar in 1st and 2nd gear, but it can't with ECU control, because it doesn't allow higher pressures in higher RPM, which is why you see only 0.7-0.8 bar boost in 1st and 2nd gear, because there is no time to raise the boost at 4000 rpm in 1st and 2nd.

Wolf66 · 11-07-07, 14:17

Originally Posted by Stuntz

CPU can know in wich gear you are in from the RPM and how fast you are traveling. But i dont know if this is the case in Q4 CPU. Will dig my head in this CPU during the winter.

There is no map related to speed/rpm and speed sensor from gearbox is connected directly to speedometer, so ECU in Q4 can't calculate the speed. Also BOSCH ABS system in Q4 is independent of ECU and it can't calculate the speed from ABS sensors either.
Boost is controled only by RPM and load/TPS angle.

Stuntz · 11-07-07, 14:21

Then th joke is in what you are trying to tell us all the time

1. and 2. are simply to short for the boost to grow. Ty

P.S. Hvala stari si kle pustu ves znanje.
Pridemo pogledat novga povža en dan :twisted:

**Steve Webb** · 11-07-07, 17:12

Originally Posted by Wolf66

Originally Posted by Stuntz

CPU can know in wich gear you are in from the RPM and how fast you are traveling. But i dont know if this is the case in Q4 CPU. Will dig my head in this CPU during the winter.

There is no map related to speed/rpm and speed sensor from gearbox is connected directly to speedometer, so ECU in Q4 can't calculate the speed. Also BOSCH ABS system in Q4 is independent of ECU and it can't calculate the speed from ABS sensors either.
Boost is controled only by RPM and load/TPS angle.

What about using the accelerometers from the suspension ECU, injector duty cycle, and rate of change of RPM?

(just having a laugh now

)

Wolf66 · 11-07-07, 17:30

Accelerometers from suspension ECU are not connected to injection ECU and they are only measuring transversal and vertical forces, not longitudinal. Suspension ECU gets the information of speed from ABS sensors.

The information, that ECU limits boost in 1st and 2nd gear came from Integrale forum and was based on information on HF Alex site, but there was mistake with translation from Italian. By the picture of boost map, which show boost map (with 4 curves) was text wrongly interpreted as curves for boost in different gears. This 4 curves are the curves for different load/TPS angle.

axaQ42 · 12-07-07, 07:25

Originally Posted by TangoQ4

I've had the exact same problem.

I have the std Garret T3 and K&N sport filter. The symptoms started all of a sudden. At first, only in 3rd, 4th and 5th gears, but then it began to occur also in 2nd. I changed the spark plugs and seemed to go away for a little while, but then it started again. also checked fuel pressure coming from the pump and changed the fuel filter, but nothing changed...

Now, after some time having this problem and being unable to solve it, I found that the dump valve isn't working anymore (didn't have the time to inspect it yet, but I don't hear the tipical "ppssshhhh" when releasing the pedal) and turbo pressure has apparently decreased quite a lot (wasn't able to measure this either, but it's notorius how it doesn't push you back anymore after going over 3000 rpm's...

Could this lack of pressure be due to the broken dump valve??

I guess lack of pressure could happen if the dump valve remains "open".

Do you have the standard Chip or custom?

If your car start to "yerk" in all gears then i guess the problem is in the igniton...have you thought to change the igniton coils?

I had a similar problem with the ex Q4(the car wouldnt run good in any gear...) and when i gave up on everything i tried to correct the idle speed(that bolt on the throttlle body) and when i corrected it(850+-30 rpm) the car started to run smoothly in any gear :shock:

Now on the white on the problem starts to happen over 1.3 bar of boost....if i floor it the car runs and pulls normally until the boost gauge hits 1.3 and then the rumble begins

If i floor the 1.gear the car goes completly normal also.

SSQ4 · 12-07-07, 12:38

Mine is cutting in 1st. 2nd. and 3rd. havent tried it in fourth or fift tough:

SS

TangoQ4 · 12-07-07, 14:18

I'll have to check out the dump valve then... I'm almost certain that this sudden lack of pressure is due to the valve being broken, but wanted to confirm this with you guys, until I had the time to inspect it (my main concern was that the turbo could be broken

)

Another thing I realized just yesterday, is that when releasing the pedal, you can hear some sort of "air pressure release" sound through the air filter (K&N conical filter), but through the dump valve... nothing at all.

Any clue?

:

**AlfaJack** · 12-07-07, 14:42

Originally Posted by TangoQ4

I'll have to check out the dump valve then... I'm almost certain that this sudden lack of pressure is due to the valve being broken, but wanted to confirm this with you guys, until I had the time to inspect it (my main concern was that the turbo could be broken

)

Another thing I realized just yesterday, is that when releasing the pedal, you can hear some sort of "air pressure release" sound through the air filter (K&N conical filter), but through the dump valve... nothing at all.

Any clue?

:

Dump valve sounds like its stuck - if its the standard one then this is quite possible as it can disintegrate...

dutchy · 12-07-07, 19:48

You said that you have checked the hoses on the map sensor.
But dit you check them if they where fully open on the inside?
My Q4 has a troublesome time behind it because there was some sludge buildup in the map hose, resulting in wrong pressure readings.
After replacing the hose, no more troubles.

Got this solution from squadra by the way.

greetings

Ruud

axaQ42 · 13-07-07, 06:48

Originally Posted by dutchy

You said that you have checked the hoses on the map sensor.
But dit you check them if they where fully open on the inside?
My Q4 has a troublesome time behind it because there was some sludge buildup in the map hose, resulting in wrong pressure readings.
After replacing the hose, no more troubles.

Got this solution from squadra by the way.

greetings

Ruud

Hmm i really didnt check it this closely....i guess i have to do it again

Bu the MS tube is very hard to access as i remember

SSQ4 · 13-07-07, 08:31

What is the easyest way to change the hose from the inntake manifold to the mapsensor?
Do we have to take of the manifold, and if so, how do one get those rubber hoses on each intake tube to fit back on...
It looks almost impossible to get at these things without taking out the engine?

SS

**AlfaJack** · 13-07-07, 09:45

Originally Posted by SSQ4

What is the easyest way to change the hose from the inntake manifold to the mapsensor?
Do we have to take of the manifold, and if so, how do one get those rubber hoses on each intake tube to fit back on...
It looks almost impossible to get at these things without taking out the engine?

SS

Its very difficult and tight but can be done in place - remove the two bolts that connects the head to the inlet manifold and get someone with a big screwdriver to gently lever the manifold apart from the head - not a lot, but just enough to get two small fingers in to connect the pipe - DONT let the screwdriver slip - it will hurt!

I know how to do this because the last mechanic to work on my car left this pipe off :x :x :x The car ran absolutely terribly!

SSQ4 · 13-07-07, 13:12

OK! i tried to losen those two bolts but the inntake manifold was stuck and i was afraid to break the aluminium so i gave up... but i guess i have to try again! Thanks

**AlfaJack** · 13-07-07, 13:15

Originally Posted by SSQ4

OK! i tried to losen those two bolts but the inntake manifold was stuck and i was afraid to break the aluminium so i gave up... but i guess i have to try again! Thanks

Hmm, there should be some little flex from the rubber connection pipes that connect the manifold to the head