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Discussion Starter · #1 ·
Hey guys, this topic received no attention over in Technical/ 8 v....maybe you all can help.
Ok here's the deal...
My 84 GLi turns over easy and idles fine at 1000 rpms. But when I hit the gas the rpms drop and the engine "coughs" a bit. I opened the hood and modulated the throttle on the throttle body to hear where most of the noise was coming from. It sounds as though there's some "popping" in the air intake boot.
Maybe a problem with the air fuel mixture unit? It kinda sounds like it's maybe trying to get more air but can't?
After the car warms up, the problem goes away. We thought it might be clogged fuel injectors, so we added a bottle of Chevron Techron and a fresh tank of 93. I've only driven about 30 miles since then, so they might still be clogged? Oh yeah and it's already got a new fuel filter.
Please keep in mind that I'm still learning, so if any of this sounds silly, I apologize.

Thanks for the help...again,
Erin
 

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Re: Air/Fuel Mixture Unit Problem?...Cold Engine Coughing (OhMyGli)

might be a vaccum leak or timing
 

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Re: Air/Fuel Mixture Unit Problem?...Cold Engine Coughing (PDX Cabby)

A vaccum leak might make sense as the expansion due to heat might seal the area that is leaking, but if the car runs perfectly when warm, I do not think timing would be an issue. Timing cannot be corrected by heat right?
-BtB
 

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Re: Air/Fuel Mixture Unit Problem?...Cold Engine Coughing (OhMyGli)

Warm up regulator.
End of story.
OK, as much as I act cocky, the only way to know is to test the control pressure using a CIS pressure test kit. JC Whitney sells one for around 60 bucks.
jamie
 

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Re: Air/Fuel Mixture Unit Problem?...Cold Engine Coughing (imaradiostar)

I'd vote for the warmup reg. as well. Probably the only heat-related FI issue.
 

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Re: Air/Fuel Mixture Unit Problem?...Cold Engine Coughing (Mk1Racer)

A third vote for the Control Pressure Regulator (aka warmup reg). If the CPR is not functioning right, then you can experience a cold start situation.
The best way to tell is with a CIS Pressure Tester. Otherwise you are just throwing $$$ at the problem. Cheers, WWR.
 

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Discussion Starter · #7 ·
Re: Air/Fuel Mixture Unit Problem?...Cold Engine Coughing (WackyWabbitRacer)

Ok, just a few more Q's.....
Will I do any other damage to the car if I drive it in its current state before I get a chance to fix it. It runs like a charm once its warm, so if I let it warm up first, will be it be ok? I might need to run it like this for a week or two.
Also, anything to look out for when doing the install on the CPR? I should be able to get one pretty easily (access to parts car). I can follow the Bentley no prob, but just wanted to know if there is anything quirky about the install.
Thanks again

Erin
 

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Re: Air/Fuel Mixture Unit Problem?...Cold Engine Coughing (OhMyGli)

Mines the same way coughs when cold then as soon as the motor heats up it runs like a top. I'm headed out to the Junkyard tomorrow for a CPR. I've been running mine that way for a few months. I don't think you'll hurt anything but I can't say for sure. Good luck!
 

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Discussion Starter · #9 ·
Re: Air/Fuel Mixture Unit Problem?...Cold Engine Coughing (OhMyGli)

PROBLEM SOLVED.
Turns out it was just the Jetronic relay. I ended up having to go to a mechanic though....couldn't check the CIS pressure on my own. Let me just say this - WackyWabbitRacer is a wise wise man. My friend and I spent an afternoon swapping the CPR and it wasn't even necessary. I've sure learned my lesson - diagnostics first, part replacement second.

At least now it runs like a dream and I'm loving every single minute of it.

Thanks for all the advice.
Erin
 
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