Need mechanics advice

[KnobMuffin]

Hi

Are there any mechanics that go through this forum?? I need some advice.

I have a VN Commodore with a 4 cylinder 2 litre Opel/GM 20SEH Family 2 engine, when I reverse the car it works fine but when I try to drive from stand still the car throws you back and forward. After the car has gotten going then I can drive it normally, the engine revs fine when in neutral.

It seems that the engine wants to stall when in low rpm and the clutch is slowly engaging. Putting more throttle on it causes more jerking. Its almost like the engine power is surging, it gets a surge of power then it looses power then gets another surge and causing rocking motion.

I have checked the fuel intake system and I have checked the air intake. I have checked the ignition leads, on cylinder 1, 3, 4 the leads are around 8.8 - 9.0 KiloOhms, the 2nd cylinder is reading 18 KiloOhms. I have replaced the 2nd cylinder lead with another lead but still the same problem (The new lead is 12.8 KiloOhms). I have tested the ignition coil by plugging in a spark plug instead of the one on the engine, I then grounded it and watched the spark, it was a orange spark. I understand that it should be bright blue. So could my ignition coil be out?? Its pretty old, I dont think its been replaced since it was made. Also the distributor looks like it could use a clean. Would that be causing my problems??

I have checked the fuel filter, thats fine. Could it just be an old ignition system??

Is it possible that low cylinder compression could be causing this??

Anything else I could try??

Thanks

[TVR-190]

not alot here no much about the 4 cyls as we didnt get them in Aus

[Ozzie]

Check to see if your coils not loose!
Common problem with those simptoms

[Zuicider]

solution - burn it

[KnobMuffin]

Check to see if your coils not loose!
Common problem with those simptoms

My coils not loose?? I have only one ignition coil and its held on by a bracket. I have checked all the connections throughout the ignition system.

[Ozzie]

My coils not loose?? I have only one ignition coil and its held on by a bracket. I have checked all the connections throughout the ignition system.

If its a single coil then you will have a seperate dizzy...
Is it an electronic distributer? If so it may need replacing.
If its the old style distributer then you may need to clean the rotor.

[KnobMuffin]

Update: I think its the TPS sensor, I tested it today, there is continuity when the throttle is closed but when I open it (past the clicking point) there is no resistance and hence a open circuit. So I think my TPS is buggered.

[KnobMuffin]

Its not the TPS sensor, I ended up taking it apart to find its a very primitive sensor. Any other ideas??

[vn calais manual]

it would have to be pretty low compression to cause this, i would perhaps be looking at the rotor button in the distributor.

[hjtrbo]

Just a thought mate, your looking thoroughly through the engine components, yet you stated in your OP that when you drive in reverse the car is fine, yet when you drive off on Drive its f#$ked. The penny dropped...???

[89berlina]

4 cylinder commodore... really worth fixing???

[ScoHar]

4 cyl commodore = petrol prices as the jap cars have.

You could try putting the car into limp mode and taking it for a drive if it doesn't surge then maybe electrical/sensor problem

[KnobMuffin]

After pulling sensor and what not apart, I found a small split in the hose between the air flow sensor and throttle body, the split was hidden because it was underneath and so I could not see it. So I tapped it up and now its working fine!! Just a simple split!!

[PaRaDoX]

check for smoke under bonnet, i hear the startfires are good at external ignition!

in all honostly i dont know if they use coils but its a ignition related problem, check your engine ground/ if it has coils your coil pack grounding straps... reason neutral will be fine is its not under any load, stick it under load and it wont beable zap enough current through with the current grounding. maybe replace the grounding strap with a new one, i did this on my supra and it fixed my issue..

[KnobMuffin]

I tested my coil by running a plug grounded to top of the engine housing and its pretty weak, so I am going to replace it with a Bosch GT40 coil, hopefully that will bring some more life into my engine.

[fasamr]

please any one can help in my ride vt v6 after cranking after the engine is started after 2 sec. i hear some noise from the engine dont kno wat is it second thing while travelling suddenly engine stops and dosent starts then after about half hour it starts normally keeps on doing this when engine stops while cranking i tried pluging out the plug lead from the coils one from each no spark while cranking any solutions i live in uae very very few mechinics to understand so please do help me

[fasamr]

the cure was the Crank shaft sensor but the sound still no idea

[matty m]

put a v6 in it