No Codes on the Vagcom?

[Scott_goddard]

Hello all,

This is my first post although I have been reading these for years! My car is running like a dog, when the revs are increased it seems to be fine. However, on tick over the car is missing badly and sometimes under load.

I have replaced the spark plugs, coil, leads, and distributor cap and rota arm. I have also bought the Vagcom and cable (shareware version), however when ran the software does not pick any fault codes.

Can anyone help? Can I use the software differently?

[Longman]

What car do you drive mate?

Assuming its a 1.8T or similar, I would be inclined to log some data from the coolant temperature sensor. You need to go to measuring blocks, and measure group 004 and column 3. See if the values you get are anywhere near what you would expect (Safe running temp 90deg etc)

Also, does the water temp needle do anything strange? (not sit at 90 or fluctuate?)

[Scott_goddard]

I am running a 2.0 GTi 8V 96 engine type AGG. I will have a look into the temp sensor!

[Crasher]

Using VAG-COM in Measuring Blocks 08, go into display group 02 and look at the figure in display zone 03. What does it say at idle?

[Scott_goddard]

This is what i get

928/min
4.08 ms
14.32 V
11 C

[Crasher]

What?

[Scott_goddard]

Sorry,

I have edited the above post! I tried to post a screen shot of Vagcom but it didn't work. One thought about the temp sensor, wouldn't this only be a problem when the engine is cold? I have the problem even when warm.

[Scott_goddard]

He is an updated reading, within attachment

[Crasher]

Can you do the same for display groups 001, 005 and 007?

[Scott_goddard]

here you go

[Scott_goddard]

Here you go, hope it help to help me!!

[Crasher]

Is the engine fully warmed up on the gauge?

[Scott_goddard]

No but it is now, thanks.

[Crasher]

Fan running?

[Scott_goddard]

Far as i know! But why would i still have the problem when the engine is cold?

[Crasher]

Well that coolant temp sender is reading low, it may be over fuelling. I think you should change the sensor.

[Scott_goddard]

Ok i shall have a look at that. Would that not show an engine code fault? Could it be the ECU relay?

[Crasher]

The coolant temp sensor won't come up as a fault if it is just reading too low. The figure in display group 002, display zone 3 is the ECU relay supplied voltage and that was a good figure as long as it stays reasonably stable.

[Scott_goddard]

Small update! I have just tested coolant temp sensor according to the haynes manual and it seems to be fine at both ends! Any other suggestions?

[Crasher]

OK, start from the beginning. Describe the problem again as how it is now but nothing about what you have done to it.

[Scott_goddard]

Right, the problem started at some lights. The engine was running fine then the revs dropped and the misfiring started. If I rev the engine slowly but progressive then there is no problem. Soon as there is a load on the engine, like going up hill then the car struggles and misfires. It is very rough when idel, the problems do not change if the engine is cold or warm.

I am thinking about removing the injectors and cleaning/replacing or trying to test them.

Thanks

[Crasher]

Removing the injectors will be a waste of time; I have never had a fault with the injectors on a Simos engine. Can you monitor that ECU voltage whilst someone else drives and see if it is stable, or log it and then review the figures in Excel.

[Scott_goddard]

Ok, i'll try that. I'll get someone to come with me while i take a drive. Will post up the figures in a bit.

[Scott_goddard]

Ok so the ECU reading was fairly stable but the O2 sensor reading was all over the place??

[Crasher]

O2 sensor reading was all over the place

If you viewed it as a line trace it would be a sine wave, going from about 0.1v to 1v and if it was a flat line (at whatever voltage), it would not be working.

I think you need to go back and look at the HT components again. The missing at idle, is it constant or coming in and out?

[Scott_goddard]

It some times goes above 1v. The missing idle is coming in and out, mostly out but when it does come in its very smooth.

[Crasher]

Using a pair of insulated pliers; pull off the HT leads one at a time to identify which cylinder is dropping out. Be careful, if you get a shock off the lead it hurts.

[Scott_goddard]

I have tried that to see which lead/cylinder maybe causing the problem, infact it was the first thing i did before replacing everything. The problem is you can ruin the coil doing that, and thats what i did! A £50 mistake! Should say that no cylinder made a difference.

[Crasher]

That will only overload the coil if it is on it's way out. The new coil, where did it come from?

[Scott_goddard]

From cambley auot factors, have never had a problem with parts from them or GSF. Although i have read that many people have had issues.

[Crasher]

Do you have any part numbers off the leads, cap, plugs, rotor, coil? It really does sound like an HT problem.

[Scott_goddard]

I shall have to get them! I will have a look tomorrow and post them. Thats what i thought and started to replace these items - it is alll very strange.

[Crasher]

Can you remember the make of the cap, rotor and leads? The plugs should be easy, just pop one out. With it idling poorly like that I am surprised no one cylinder showed up as being at fault. It would be nice if you could get it on an old fashioned diagnostic machine (Crypton or such) and see which cylinder is playing up. The thing I find strange is no lambda errors if the engine is running that poorly, if the lambda signal was fluctuating it means it is running and the exhaust gases can't be far out if it is. Go into measuring blocks 08, display group 005 and look at the eight digit (what can be called bin bits) display figure in display zone 4. This should show 0000101 and the last digit must be regularly swapping from 1 to 0. The voltage in zone 3 should fluctuate from 0 to 1.1v at least 30 times per minute.