I have an ’89 Fox that is killing me. Here’s what it does: When you turn the key, it cranks right up IMMEDIATELY and seems to run fine….but for only about 2 seconds. It seems like after the cold start system finishes doing it’s thing and the car is supposed to start idling on its own, it starts to run REALLY, REALLY badly. The engine is physically shaking in the engine compartment which shakes the whole car. If you press the gas pedal rather quickly, the engine slowly speeds up still running terribly. It ALMOST dies but when you let off the gas it sputters and barely recovers and then continues running badly again. I have been working on this thing for weeks and weeks trying to breathe new life into it. I was working on it so long some nights that I actually saw the sun come up and finally just went to bed at 8AM the next day! Yes, I have the Bentley manual and I have done so many tests that it told me only to find that, from what I can tell, they just about all passed. This includes:

- COOLANT SENSOR: measured at nearly 2000 ohms on a hot day
- THERMO-TIME SWITCH: gave cold start valve juice according to the chart in the book
- COLD START VALVE: Sprayed gas according to the manual.
- FUEL PUMP RELAY: Good
- ALL FUSES: Good
- IN-TANK PUMP: Got 530cc at 10 seconds
- MAIN FUEL PUMP: Tested at 12.44 volts. Got OVER a liter at only 23 seconds. I actually had to stop at 23 seconds (instead of 30) because the one liter measuring cup I was using already over flowed. Not sure if this result is actually good because I got way more than the test said.
- AIR FLOW POTENTIOMETER: Pins 1+2 = 4,850 ohms, Pins 2+3 = 850 ohms. With air sensor plate fully up I got 5,450 ohms
- DIFFERENTIAL PRESSURE REGULATOR: Cold Running Enrichment = 85mA, After-Start = Peaked at 160mA and slowly fell back to 85mA after about a minute
- COLD ACCELERATION ENRICHMENT: started at 85mA, shot up to 140mA when air sensor plate was moved and then fell back to 85mA
- CONTROL UNIT INPUTS: All passed EXCEPT possibly one. I did have a question about the ninth test down: Regarding the O2 sensor - it says connect green wire to black wire and you should get NO continuity. Well, first of all I don’t have a green wire at the O2 sensor OR either of its wire harnesses. My O2 signal wire is a big, fat black wire that is by itself in it’s own harness. The other accompanied wire harness has a brown and a black/green wire. Those two wires are for the heater element of the O2 sensor but NEITHER is solely black. Well, I still tried my signal wire with the black/green wire to see what would happen and instead of no continuity; I got about 10 or 11 ohms. I am NOT pleased about the Bentley being off on the wire colors regarding this because I am left not knowing how to test the ninth test down and testing/troubleshooting is why I bought the book. If anyone knows more about this particular test, I would love to hear it because I’m lost on it.
- NEW SPARK PLUGS AND WIRES
- NEW BATTERY AND ALTERNATOR
When grounding the spark plug wires or center distributor wire, I get a HUGE spark and I felt it once too….OUCH. I don’t think weak spark is an issue as the car starts immediately but just runs crappy afterwards.

I have not checked the fuel pressure because I do not own a gauge. I will probably have to get one. I have not checked the timing with a light because the manual says the engine has to be at operating temperature. Well, the car runs like such crap that it’s difficult to get it to operating temperature. It shakes so much that I am actually afraid it’s going to fall off the jacks its sitting on. I have not checked the compression because it is also supposed to be checked warm. It has fre

 

As for a history of the car: I received the car in a situation where it physically wouldn't go in gear. The engine itself showed no signs of issues except it smoked a little from what I think are leaky valve seals. IT PREVIOUSLY STARTED UP AND RAN JUST FINE. A car that ran fine but wouldn’t go in gear still will do you no good so my plan was to learn on this car on how to put in a new clutch, go through the transmission to see how it looked and to repair/replace the shift linkage parts. I found that the clutch really wasn’t that worn but since I was in there, I resurfaced the flywheel, replaced the disc, pressure plate and both bearings. The reason it wouldn’t go in gear is because the shift linkage was COMPLETELY worn out so I replaced all the bushings and it was good as new. While I was in there I also replaced the rear engine seal which hadn’t been leaking but I was already in there so I did it. I am really trying to do this car right and by the book.[/align][/align]The ONLY thing I did as far as the motor is concerned is remove the oil pan, clean it out and clean out the oil pump and it’s screen (which wasn’t blocked). I also checked the tolerances of the lower part of the motor (side to side play, etc) and they checked out fine and I made sure all the lower nuts (connecting rods, etc) were within torque spec (and they were)[/align][/align]So when I put the transmission back in I thought I was pretty much done with the car aside from checking valve seals, putting on a new valve cover gasket and changing the timing belt (cuz I always wanted to change one of those too…lol). In no way am I “half-assing” this car. I have put some money and SERIOUS amounts of time and effort into this thing which is why this situation is very frustrating because I pretty much should be done but now this was an unexpected set back. I know a decent amount about cars and stuff but, for example, I had never changed a clutch and always wanted to know how it’s done so I have been using this car to learn on.[/align][/align]I’m trying to troubleshoot by process of elimination:
- I’d like to check the flow of the injectors: How do you get the fuel injectors out? Mine would not just simply pull out.
- Running it with the O2 sensor unplugged had no noticeable affect on how it ran...still crappy.
- If the timing and/or spark quality was messed up I don’t think it would start up right away and then run fine for 2 seconds. So it seems to eliminate that.
- If it starts up right away then it seems to eliminate the entire cold start system which has already checked out anyway.
- If it runs bad AFTER the cold start system turns off then it seems like fuel delivery isn’t right. All the electrical tests have been done as noted in my first post and checked out great. The only one is the ninth test down regarding the O2 sensor (Section 5, page 43 of my Bentley) I still need advice on this test.
- Could this be fuel pressure? If so, is it possible to have fuel pressure problems even though both pumps delivered well above the minimum amounts AND the electrical tests checked out?[/align][/align]I should offer a reward for the person that finds the problem…lol I’m putting so much effort into this thing that I feel like its sucking the life out of me. : )[/align][/align]John[/align]

 

Your problem may be due to poor electrical connections. Check all of your ground wires first. You have an 18 year old vehicle. After 18 years of heat under the hood, water (and possibly salt if you are in the north) the wires can become frayed near the terminal that is crimped onto the end of the wire. Also the area of the frame or engine where the terminal makes contact, can become corroded creating a poor ground.

I have an 88 VW Fox and experienced virtually the identical behavior you are describing. The car would start right up perfectly and run well for the two seconds that the thermo time switch was activating the cold start injector. After that the engine would either stall or barely run. Giving it gas usually caused it to stall. If it would keep running (badly) for long enough I was able to work the gas pedal and eventually get it to run better but still missing some.

I discovered the problem by accident. When the car was running halfway decent, I was looking at the wiring to the differential pressure regulator. I unplugged it and the car reacted by getting rougher. That indicated the differential pressure regulator was working correctly. I then jiggled the connection to the O2 sensor and noticed that the engine immediately started to run rough. I thought the problem was the connection to the O2 sensor. As it turns out, when I was moving the O2 sensor connection, I was inadvertently moving a ground wire. After discovering the ground wire was causing the problem it was obvious that the wire was in poor condition right where the connector crimped to the wire.

After fixing that ground wire the car has run very reliably again.

Note that earlier I had problems with the alternator not charging the battery. After replacing the alternator then a few belts, I discovered that the primary grounds (large cables) where nearly broken off. After changing these grounds the alternator worked perfectly.

 

To get the fuel injectors out there is a tool that makes it relatively easy:

http://www.worldimpex.com/parts/oem-...123_12494.html

If you dont buy one maybe you could fabricate one yourself, it doesn't look too complex.

When I removed mine I was not aware of this tool. I struggled to get them out using a pair of vice grips to lock onto the injector then using a large screwdriver to lever the vice grip (and injector) using the top of the engine as the pivot point. It is very important that the applied force moves the injector straight out.

 

I have the car running absolutely perfectly now. I changed a bunch of parts as a course of maintenance but there were two MAIN reasons the car would not run right. The first was the auxiliary air valve (it wouldnt idle right) and the second was replacing all four injectors. The new injectors made the car run awesome. they weren't cheap : ((

 

Glad to hear that you have it running now. I had to replace my injectors a couple of years ago. When mine went the engine didn't run quite as bad as when I had the ground wire problem.

A good place to get parts for your fox is http://www.autohausaz.com I buy almost all my parts there now.

They have injectors w/the seals for $56 each. Free shipping on orders over $50

 

Yep, thats precisely where i got them. I love autohausaz.

 

My 90 fox is sick? It is similar in that it will not start. I have replaced the entire alternator because it was not fully charging the battery to its potential, thought the brushes were bad. The whole shaft was shot. Once it was replaced the car would start on and off perfectly. Then drove it home about a 20minutes drive and parked it for the night. The next morning it would not start? I am not to familiar with vw in general so I am not sure what the most common problems would be? And this is my first fix up car. Any help?