vz aloytec engine problems????

[wish_i_had_an_8]

hey guys, to start off iv been folowing just commodores for the past fue years but this is my first post so go easy on me if im posting in the wrong section or something.

iv got a vz calais (190) wich has recently started playing up, under full throttle at about 4000rmp the engine starts to cough and splutter. still reving up but the speed of the revs seems to stop almost like a flat spot and then continue to climb. its most noticeabull at 4000rmp but does hapen between 4000 and 6000 intemediately.

i only started to notice this after putting a full exhaust system on my car (x force extractors high flow cats and 2 1/4 twin) my car also has a cpr6 manifold on it and the car hasnt been tuned yet... (i never noticed it playing up when i just had the cpr6 manifold and standard exhaust)

basicly im just wondering what people think of this problem and weather a tune could more likely fix it or if they think i may have engine damage..

any responce would be appreciated

regards josh

[torana355]

Have you checked the Coils?

[richardpalinkas]

possibly something to do with the fuel pump/ filter. i think i would replace the fuel filter first to see if that fixes it

[wish_i_had_an_8]

Also the car is on petrol/liquid injection gas. And it does ot on petrol and gass im stumped...

[RiCeY]

Has it thrown an engine light/warning?

[richardpalinkas]

not sure if this would help, but if we get all the facts together, it only happens when its at a certain rpm (high), and it has dual fuel and does it with both, so im guessing that would cancel the fuel filter and pump. so just gotta think what links in both of them together that only happens when the engine is at high pressure?

my next guess would be the injectors? or does gas not run through them?

[bcw61]

my next guess would be the injectors? or does gas not run through them?[/QUOTE]


On dual fuel vehicles (assuming the factory IMPCO Sequent 56 is fitted), the gas vapour injectors are seperate to the petrol ones (an extra six gas injectors are fitted beside the regular petrol injectors). If the identical problem is occuring in both petrol & gas modes, then that would seem to eliminate the majority of the fuel system, apart from some of sensors. Could possibly be an O2 sensor problem considering that you have disturbed/replaced the exhaust system and by your admission, the problem seems to have occurred after that time.

Alternatively, I would also be looking at a breakdown somewhere in the ignition system, or perhaps camshaft phasing issues.

My thoughts only.

[alex2_s]

sounds like coils definitely....

[wish_i_had_an_8]

Thanks for your replys guys. Yes it hapens on petrol and gas and yes it has a different set of injectors for gas im thinking at this stage that it is most likely the coils or an o2 sensor problem since the alloytec 190's had 4 cats wth a set of sensors after the first set of cats and the other sensors behind the second set of cats. Now, because my car only has 2 cats the first set are picking up non filterd exhaust since there on the engine side of the cats wit h makes it throw a "check powertrain" code but thats the only code i get and no no engine light

[keeny]

i had the same problem in my vz calais and it was one of the coils, new plugs wouldnt hurt either. runs much better now

[bcw61]

since the alloytec 190's had 4 cats wth a set of sensors after the first set of cats and the other sensors behind the second set of cats. Now, because my car only has 2 cats

Just to clarify: both the Alloytec (175) & Alloytec 190 have only a total of 2 catalytic converters fitted. The Alloytec (175) has an O2 sensor (2 in total) fitted only to the front of each catalytic converter, whereas the Alloytec 190 has O2 sensors at both the inlet and outlet of each catalytic converter (4 in total), to meet the Euro III emission standards.

[impulsive]

Fouled plugs? This happened to me changed them away she went. J
this occured to me when I used injector cleaner