Ok I already know that my 91 VW Jetta GL needs an exhaust manifold replaced, and I am wondering if that would cause it to lose power at 2500 rpms? It will be going just fine then if I let it get above or at 2500 rpms it just bogs down, and will not gain speed no matter how much gas I give it, the CEL comes on most times when this happens, but if I push the clutch in and rev it past 2500 to like 3000 rpms the light goes off, but still lacks power. I changed plugs, wires, cap, rotor, cleaned intake, ran injector cleaner, changed fuel filter. I even replaced the catalytic converter, to no avail. I just bought car the car, and drove it 75 miles to get home, and this problem never arose, it did surge a little but never lost power like this. If any one can give me a few things to look into I would greatly appreciate it. Thanks
Another thing, the car did set for a year with a full tank of gas in it, but I used most of that up and put fresh gas in it.What could be causing my 1991 Volkswagen Jetta GL to be losing power like this?
Good Jokes, Cars, and Great Sex all depend on Proper timing.
If you haven't timed your car then do so now.
To time the 91 you have to have the engine up to temp.
then using a timing light on number one plug.
unplug the CTS sensor (blue one on the side of the head upper water outlet flange) and rev the engie 3 times over 3000 rmp.
Holding it steady at 2250 RPM, then adjust the timing to 6degrees BTDC. (there is a timing hole in the transmission housing.
I would then replace the CTS sensor (cheap at Napa ) as that is known to cause issues. If you haven't replace the fuel filter now would be a good time to do it.
If you head a whine from the rear passenger side wheel arch when this happens, then you have a restriction in the fuel as in the in-tank fuel pump (also known as the fuel-transfer-pump) is going out or gone out, and causing a restriction to the main pump.
This year of jetta has 3 fuel pumps one in-tank, that feeds to the primary.
I would also highly suggest that you remove the vacuum line that runs from the throttle body to the fuel pressure regulator (on the rear of the throttle body) and see if there is raw gas in it. That is gas that drips out of the hose, if there is then the Fuel pressure regulator is bad.
I would also strongly recommend that you replace all the vacuum hoses on the car as any slight leak causes them to act the ***.
Lastly, make sure that the big black hose from the air filter box to the throttle body is not wholed, and that it is tight to the throttle body and to the airbox.What could be causing my 1991 Volkswagen Jetta GL to be losing power like this?
It's the manifold. Why did you throw parts at it, when you know it is the manifold? Also, you should have had the seller have the manifold repaired/replaced prior to purchase.What could be causing my 1991 Volkswagen Jetta GL to be losing power like this?
I'd take it to a mechanicWhat could be causing my 1991 Volkswagen Jetta GL to be losing power like this?
You already know it needs an exhaust manifold? How do you know this. I think you are mistaken or foolish. Have you had the CEL scanned for a code????? Yeah, there is a lot of data missing here. Still could be other stuff.
Timing, Mass Airflow Sensor, Badd parts in the ignition(out of the box or installed poorly) Plugged muffler from a FAILED catalytic converter.
Time to go to a shop. Pretty much any shop can work on these so skip the VW Dealer.
Jack, 2003 GLI, VW since 1959, ASE Cert Auto Tech since 1978What could be causing my 1991 Volkswagen Jetta GL to be losing power like this?
I think it's fairly obvious why the previous owner sold it , the last time I heard of this , the cam belt had been replaced three teeth out from where it should have been, why do you think the exhaust manifold needs replacing? any problem with it would be very obviousWhat could be causing my 1991 Volkswagen Jetta GL to be losing power like this?
Your VW is to old, visit mechanic.What could be causing my 1991 Volkswagen Jetta GL to be losing power like this?
Wow Justin!! Without more info about the motor, type of fuel injection, etc, I would not be able to be of much help.
However, the bogging down could be caused by a fuel restriction of sorts. In SA, we had the mk2 in 91 still and they came with motronic injection. Low fuel pressure compared to the older K jetronic system.
My suggestion would be to get it to a good honest mechanic and let him take a look. To many things have been replaced now and nothing has changed. The manifold won't affect it as drastically as this.
Standing does a fuel injection no good at all and they are difficult to understand if you are not experienced..
Good luck.
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