91 Jetta coupe-gutless

check out the boot from the airbox to the throttle body it might be cracking

or fuel pressure regulator leaking fuel through vacuum hose.

a coupe huh? got a picture?

later, dave (One out of many daves)

Did you replace the distributor too? Try that too, and don't forget a new rotor and cap.

Replace those two temperature sensors (one is blue the other is black) on the main rad line... These caused all sorts of problems with my 1991 Golf, no power below 3500rpm... They are dirt cheap, even from a dealer.

checked ALL intake pieces and vacuum lines,theyre all good,no fuel leakage anywhere,the wires distibutor cap and rotor are almost brand new,I did have to replace the coil recently (it died overnight too??) replaced it twice just to make sure after this happened lol, after driving it today i noticed it was behaving as you posted no power until the higher rpm,and once i was up to speed it seemed somewhat normal, but still not the jazz it should have,I'll try replacing those temp sensors,I'm really wonding about the knock sensor the wire looks fried, anyone have one of them go b4? Theres also the issue of the muffler it getting progressivly louder, its where the manifold meets the pipe so I assume its the gasket, maybe the other spring clip is missing I havent seen it from underneath yet, but I'm wondering if that would cause or contribute signifigantly to the gutlessness? lol when ever I find the source of this problem and fix it, the old peice is meeting DR HAMMER!!!

ck that the timing belt has not jumped time?

i doubt it has,but ill check it if it becomes necessary(I dont have the gear/know how lol)

i doubt it has,but ill check it if it becomes necessary(I dont have the gear/know how lol)

Yes the Knock Sensor will affect the spark advance and will cause a loss of engine performance. You can check that with an adjustable timing light and a Bentley manual.

A clogged exhaust will cause more exhaust noise at the manifold if it has a leaky gasket. Also a leak in front of the 02 sensor might cause running problems too.

Remember that the fuel pressure regulator can leak fuel and it will go into the vacuum line and then into the intake manifold.

good luck

My wife had a 91 Jetta with Digifant. It served her very well for 11 years before trading to a new VW. It was absolutely gutless from day one to when it was sold. The engine felt like it had no more than 50 HP. I personally checked and re checked everything I could in those 11 years. Everything was within spec. The head gasket went at about 150,000 kms. I personally did the job, and very carefully checked the head when off the car, personally re grinding the valves etc, etc. Mechanically that car was perfect and the ignition timing etc bang on. I always blamed the Digifant as I could never find anything else. david

will be fixing exhaust and replacing coolant temperature sensors today will update with results,dont have the gear to check timing, the 02 sensor was never hooked up so thats not the prob, vacuum lines seem to be gas free,we will see about the exhaust when i fix the leaky gasket

That's characteristic of the cam sprocket being on backwards. Lining up the timing marks will under those circumstances result in valve timing retarded by about 30 degrees. The engine's a real wimp until you thrash it over 5500 rpm from where it pulls strongly to the limiter.

My GTI was also poorly - after the head gasket blew (my fault) the head was done (new valve guides, etc). Even my mechanic couldn't figure it out; given that it's not necessary to take the sprocket off the cam in order to do the reconditioning he'd sub-contracted out. Cost *him* about 40 hours - over a period of 6 months to diagnose.

In the end; the straight-edge across the cam lobes at TDC told the full story. i.e. cam and sprocket were mis-aligned.

Everything you checked.

So did the mechanic in my case.

well unless the cam sprocket can change direction by itself and overnight then thats definately nort the problem as the car DID work fine 2 weeks ago(lots of power)anyways I changed the temp sensor today and did the exhaust,quieter a tiny bet better,but still lacking,(definately no cat clog)tested the knock sensor,tapping on it lightly made the timing change,so thats not it,o2 sesnor was never hooked up so thats not the prob, vacuum lines seem clean and gas free,the front motor mount has been going for some time, maybe it has something to do with it, by yanking wires or something,so I'm still trying to figure it out,but thanx so far, everyone is giving many more ideas

btw anyone know what kinda ohms reading i should get from the coil though i replaced it twice niether were new,they were werking but who knows

Did you check the CO before the cat. conv.? I have had to adjust the screw inside of a few of the airflow boxes to get some engines to run better. If the engine runs a little too rich, it will not have that good power you want. I have seen at least two bad airflow boxes.

I have seen too many wiring problems at either the grounds to the intake/cyl. head or at the throttle switches.

BTW Most Digifant IIs that I have seen have great power! Of course these engines have a working 02 sensor! 8^)

later, dave (One out of many daves)

one other weird item i noticed when fixing the exhaust system was a threaded hole above the o2 sensor on the manifold, thats where all my noise was coming from,the gasket was shot too but it was still loud with the new gasket,plugged the hole the car is quiet as normal

I'm not sure what you mean by the CO?I replaced the whole air intake system already, if you mean the ground at the cylinder head, if you mean the one by the valve cover, you may be right, because it is loose one a little oily, I'll try to clean up all the grounds i can find,cause ya never know,the gas consumption is alot worse now aswell just remembered now to mention it, but it may be a pointer

this should explain a few things about the emissions on autos. ;-)

meh no emmissions testing round here,but yeah I do think my engine is running rich