[Samana76]

Hello everyone,

Yesterday I went for a fantastic drive through beautiful mountain roads with my GTV6. Something was happening that I do not recall was occurring before.

Driving up the twisty roads sometime I would find myself in second gear at about 20mph driving uphill. The car would slowly accelerate, but the engine would jerk repeatedly and quickly until 3000 RPM, after which it would shoot off as if it where a turbo engine. It did this all day long in any gear - in fact also from stand still in first gear.

Also, driving down the mountain, when I would let go of the accelerator (usually because there was a much slower car in front of me ) my GTV6 would "pop" from the exhaust constantly, multiple times a second, until I pressed the accelerator again. This too I do not recall it occurring in the past.

For some reason I'm thinking the engine might be running too rich, but I am not that knowledgable of these symptoms. So I am asking you much more experienced and knowledgable subscribers of this forum for your input.

What could it be and how can I fix it?

Thank you all for your suggestions and help.

Cheers,
Igor

 

[ghnl]

Check that the air duct from the Air Flow Meter to the throttle is secure and that it has no rips/tears.

 

[Gubi]

Yeah, most likely you've got an air leak somewhere.

 

[alfaparticle]

Or a worn spot on the AFM contact strip.

 

[Samana76]

Thank you all for your quick replies. I did open the AFM and the strip seems in great condition. I did rotate the wheel about 6 notches counter clock wise (opening the flap a little). This seems to reduce the problem significantly.

I also see some hairline cracks on the undulated rubber hose, but don't see any cracks splitting it to let air in (I might replace it just in case).

Now that I think about it, though, it's been a while that I notice that the car really takes off at 3000 + rpm and is sluggish below (although I never had the jerkiness described in the original post).

Thanks again for all your help.
Igor

 

[gmjohns]

Sounds like you need to get a wideband sensor and gauge. I have just finished troubleshooting a similar problem. It could be any number of things but I can tell you that here are some common problems.

1. Check the connection at the distributor from the fuel module as this connection can arc causing intermittent stuttering etc. until it completely fails.What appears as one wire is actually two leads. they tend to arc right at the bosch connector on the distributor. if you can see wire, tape the exposed to isolate the 2.

2. It could be that the car is running lean under normal driving but when you engage the throttle position sensor (60% pedal) the mixture gets richer instantly which might explain the "turbo" effect.

3.An air/vacuum leak somewhere. If you have cracking in the baffle, there is a good chance that it's leaking somewhere (typically where you can't see) I suggest getting some spray starter fluid or WD40 and spray the hoses around the intake while running. If the idle speeds up, you have a leak.

If none of this proves to fix the problem, the wideband sensor can help you determine the air/fuel mixture which can help you understand where to look. There is an O2 sensor with the wideband feature that you can use in place of the OE o2 sensor so you do not need to add a bung to the exhaust. Hope this helps?

 

[Gubi]

Thank you all for your quick replies. I did open the AFM and the strip seems in great condition. I did rotate the wheel about 6 notches counter clock wise (opening the flap a little). This seems to reduce the problem significantly.

Yeah, don't do that. You're just screwing up the mixture to compensate for something else that's screwed up, most likely an air leak.

If you can't find a leak, go through the whole L-Jetronic troubleshooting guide, make sure all that stuff is good.