# help! suggestions on tracking down CIS-E power loss problem - limp mode? cold weather related?



## eltopo (Jun 20, 2007)

Sorry guys, I'm here begging for some advice on what I should check first to try to find the cause of a problem on my 1989 Fox (approx 150k miles, standard US model CIS-E injection).
The symptom is loss of power when driving at freeway speeds, about 10-15 minutes after starting the car. The car never stalls but when the problem occurs it cannot produce enough power under load to maintain road speed (in idle, the engine will rev). Typically, what happens is that I leave my house, drive for about 3 miles in the city, get onto a freeway and things are normal for about 5-10 miles, after which point the car will suddenly lose power. I would term the behavior as a sort of limp mode; I imagine that only minimal fuel is being delivered. The car does not recover from this condition if I keep driving on the freeway; however, it will sometimes recover if either (1) I pull onto the shoulder, turn the engine off for a few minutes and then restart; or (2) I get off the freeway and continue driving on city streets, stopping at traffic lights, etc- it usually starts acting normal again several minutes later.
This started happening sporadically last fall and I suffered through it all winter long. However, the problem did not recur during the entire summer. Last weekend we had our first cold days of the season (lows around freezing), and the problem came back. So I'm wondering if this could be related to outside temperature? (although I don't know what mechanism would explain that)
I've done the typical regular maintenance on the vehicle (oil changes, air filter, spark plugs, distributor cap + rotor). Checked and reset ignition timing last fall when the problem first started to occur but this did not make a difference. The fuel transfer pump has been replaced but I believe the primary fuel pump is original. Could a fuel pump fail in this manner (causing the car to limp along at times, but then returning to normal)? It seemed to me more likely that something is wrong with the fuel injection control.
Possibly related problem: for several years at least the car has had trouble running immediately after a warm start. Everything's fine after cold start (leaving the car off overnight, etc) but I tend to get low power and rough running after warm start. This clears up, however, after a period ranging between 30 seconds to maybe a few minutes. I assumed that this had something to do with residual pressure in the fuel lines, etc. Anyway, this warm start problem has been going on for years (longer than the loss of power problem) so I'm mentioning it only in case it has any relevance to the loss of power.
Does the CIS-E in the Fox have a 'limp mode' which could be triggered by a bad sensor, bad ground, bad wire or bad ECU? Or could this be a mechanical failure somewhere in the injection/intake box?
I would really appreciate it if anyone had suggestions for what I should be checking out first. I was planning on making an attempt this weekend to go through the Bentley book and try to check sensor voltages, etc. If the symptoms I've described ring a bell for any of you out there, it would be a great help and I'd definitely owe you a beer if you're able to point me toward the way to get this figured out.
Thanks a lot.


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## PASHAT (Oct 23, 2006)

*Re: help! suggestions on tracking down CIS-E power loss problem - limp mode? cold ... (eltopo)*

First thing I would do is, using a harness, connect a multimeter in series and check the mA value at the DPR. It should be fluctuating and around 10. Do a search on DPR, mA, Harness and you should get a link to a picture that shows how to set this up. You might need to buy a few connectors from a junkyard.
Check carefully for vacuum leaks. Pull the injectors and observe the spray patterns and replace the injector seals while you have them out.
That would be a start.


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## eltopo (Jun 20, 2007)

*Re: help! suggestions on tracking down CIS-E power loss problem - found vacuum leak!*

I was able to spend some time going over my car this weekend. I did not test the DPR current, because I'm too chicken to use plain alligator clips on the connectors and risk shorting something out. (I'd like to get a harness at some point but I will have to source the necessary parts first, etc.)
I went through the Bentley and looked at their troubleshooting charts to get ideas. I checked the coolant temperature sensor and the airflow potentiometer (because those were easy to do with a multimeter); both tested okay.
I realized that I had never removed the boot on top of the airflow sensor plate (since I've had the car). So I figured it might be interesting to check for mechanical problems there. I pulled the boot and found... lots of oily dirt and grit:








hmm, looks ugly...








Thinking this might have caused a mechanical restriction, I cleaned it up with some carb cleaner:








I talked with my dad and he pointed out that a likely source for the oil would be the crankcase vent, and he suggested that I should take off the hose between the CCV and airbox and clean that. So I started taking that apart and found a vacuum leak I had missed before:








The breather hose elbow had ripped along one of its outlets. I had checked for vacuum leaks all over the engine but must have missed this one because the torn part was on the underside of the elbow (which you can't see without removing it). Fortunately, this part seems to be widely available and not Fox-specific:








breather hose elbow (026103247): http://www.busdepot.com/detail...03247

So my thinking is that the tear in this part would have resulted in a nice vacuum leak and could have caused my running problem. And maybe the rubber gets more brittle in cold temperatures, explaining why it only seemed to happen in the winter? Plus, the hole in that tube could sucked dirt right into the intake, resulting in the grit on my airflow sensor plate, right?
I sealed the elbow temporarily with silicone and I'm going to replace it as soon as I get a new part. I have a few questions if someone would mind giving me more advice:

1.Should I take the top off the fuel distributor and look for more dirt? Or am I best off leaving well enough alone at this point? (The airflow sensor plate seemed to move okay)
2. Unrelated: my fuel injector shrouds are loose. I can spin them with my fingers. I bought new upper injector O-rings because I was planning on testing the spray pattern and replacing the seals while the injectors are out. Should I also get new shrouds and lower seals and replace those too? Or just tighten the existing ones?

Thanks a lot,
Chris


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## PASHAT (Oct 23, 2006)

*Re: help! suggestions on tracking down CIS-E power loss problem - found vacuum leak! (eltopo)*

That fuel plate was UGLY! Nice job on cleaning it.
Don't pull the dizzy off if you don't have to. You can't adjust much there and it should not need adjusting. You can see everything from the bottom if you pull the top off your air box. 
Disassembling your fuel distributor is a big No No.
That fuel plate looks a little low....should be about 2mm from the edge of the cone, but I wouldn't monkey with it until you see how it is running.
Replace the lower 0 rings. They are cheap and often come as a kit. I don't know about the shrouds...someone else will have to tell you about those.
That vacuum leak was massive.


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## eltopo (Jun 20, 2007)

*Re: help! suggestions on tracking down CIS-E power loss problem - found vacuum leak! (PASHAT)*


_Quote, originally posted by *PASHAT* »_
Don't pull the dizzy off if you don't have to. You can't adjust much there and it should not need adjusting. You can see everything from the bottom if you pull the top off your air box.
Disassembling your fuel distributor is a big No No.


Right. The Bentley mentioned checking the control plunger and cleaning if necessary. I assume that it's best to leave that alone unless I have evidence that there's a real problem? (My concern was whether some of the dirt on the air plate might have migrated to the control plunger)

_Quote, originally posted by *PASHAT* »_
That fuel plate looks a little low....should be about 2mm from the edge of the cone, but I wouldn't monkey with it until you see how it is running.


So far so good. I haven't yet lost power while driving like before but I can't say that the engine seems 100%, either. I'll replace the breather hose elbow and see how the car runs after that. We checked the timing and idle bypass last year but that would have been with the vacuum leak, so I might recheck the idle speed once I get the new hose in place.

_Quote, originally posted by *PASHAT* »_
Replace the lower 0 rings. They are cheap and often come as a kit. I don't know about the shrouds...someone else will have to tell you about those.


I haven't pulled the injectors yet so I'm not 100% sure which part is which. I'm guessing that the lower O-ring would be the small seal at the tip of the injector e.g. in this picture:
http://www.autohausaz.com/secu...5.jpg
I have a recurring running problem immediately after a warm start, so I assume that I've got a leaky check valve somewhere (fuel accumulator? injector?). But the car always runs okay at least after a minute has elapsed after warm start. Cold start is generally perfect.
Thanks a lot,
Chris


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## PASHAT (Oct 23, 2006)

*Re: help! suggestions on tracking down CIS-E power loss problem - found vacuum leak! (eltopo)*


_Quote, originally posted by *eltopo* »_
Right. The Bentley mentioned checking the control plunger and cleaning if necessary. I assume that it's best to leave that alone unless I have evidence that there's a real problem? (My concern was whether some of the dirt on the air plate might have migrated to the control plunger)

This is next to impossible. There are o-rings on the plunger that isolate it from the airbox. Otherwise, fuel will leak out (which it often does as the o rings wear out)


_Quote »_
I haven't pulled the injectors yet so I'm not 100% sure which part is which. I'm guessing that the lower O-ring would be the small seal at the tip of the injector e.g. in this picture: 

That is the lower o ring, but it is the upper one that creates the vacuum problems if it leaks. To remove them, all you do is remove the clips near the intake (if there are clips) and pull them out. It is easy to do unless they are really stuck. Then you still have to pull, but you have to pull harder! Might as well replace the darned o rings when they are out.


_Quote »_I have a recurring running problem immediately after a warm start, so I assume that I've got a leaky check valve somewhere (fuel accumulator? injector?). But the car always runs okay at least after a minute has elapsed after warm start. Cold start is generally perfect.
Thanks a lot,
Chris

Your injectors cannot....or should not be able to.... provide fuel to the engine if the fuel plate is down. Could be a temp sensor. Could be an incorrect adjustment of the fuel plate. Could be a leaky o ring on the fuel dizzy....but it would have to REALLY leak, and you would notice that on the top of your air filter....could be the cold start valve.
There are no other points of entry for fuel to the intake other than injectors, the fuel dizzy and the CSV that I can think of. Fuel accumulator can't leak into the intake, but too much fuel pressure might cause this. Blocked return line?


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## eltopo (Jun 20, 2007)

*Re: help! suggestions on tracking down CIS-E power loss problem - still looking*

Following up on this... I still haven't figured out what's wrong with my CIS-E Fox, unfortunately.
I replaced the cracked rubber breather hose with a new piece. The car drove OK for two weeks or so, but the weather was pretty warm during this period. As soon as it got cold again (last weekend), the power loss problem returned. Does this problem sound familiar to anyone? Here's the best description I can come up with:

On Saturday, I started the car and it ran fine- I got onto the freeway and drove about 10 miles- at which point I lost acceleration and couldn't get above 45 mph or so.
I pulled off the freeway at the next exit, took about 2 minutes to do a U-turn, stopping at various traffic lights, and then got back on the freeway. At this point I was able to accelerate normally.
I drove for another 10 miles and the car lost power once more. I pulled off the freeway again, did another U-turn, taking a few minutes to turn around, and got back on the freeway. Again, the car was back to normal. I drove for another 10 miles and got to my destination, but I assumed that it would have died out again had I stayed on the freeway.

At no point did I turn off the engine; the power loss problem seemed to "self-heal" during the few minutes that I was off the freeway, turning around on surface roads.
The best I can describe the power loss is that it is preceded by "cutting in and out" of power, followed by an eventual total loss of acceleration. The car will run for 5-10 miles normally, and then the engine begins to cut in and out. This may go on for a few miles, and eventually I just lose all power. I assume that the power loss is the result of a lack of fuel delivery- is there any other possibility?

The car never stalls or dies, even when in the loss-of-power state. 

I am becoming increasingly convinced that cold weather is the trigger for this problem, mainly because it didn't happen all summer, and it plagued the car all last winter, and so far, each of the two times it's happened in the last month have been on cold days.

I guess I will keep looking over the car for more vacuum leaks, in case I missed something. Are there any clever ways to do this?
Could this be an issue with the main fuel pump? I believe mine is original, so it would be about 18 years old with 150k+ miles on it. I have access to a newer pump (1-2 years old) which I could try swapping in for mine. Would cold weather be a possible trigger for the main pump losing output? (The car doesn't stop running, so it can't be a total lack of pressure) Would a fuel pressure gauge tell me anything useful?
I haven't replaced the injector O-rings yet, but I suspect that they may be bad. I think my injectors are loose- they can be spun easily with fingers. Should the injectors be held firmly by the engine block? I have the CIS injector puller on order- I wasn't able to get mine out with "gentle force" and a screwdriver, and I didn't want to break things. I'll replace the O-rings and check the spray pattern when I get the injectors out.
I also have the DPR test harness on order- I'll get it next week and will be able to take a look at the current reading next weekend.

Thanks a lot for any suggestions,
Chris


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## PASHAT (Oct 23, 2006)

*Re: help! suggestions on tracking down CIS-E power loss problem - still looking (eltopo)*


_Quote, originally posted by *eltopo* »_
I haven't replaced the injector O-rings yet, but I suspect that they may be bad. I think my injectors are loose- they can be spun easily with fingers. 


WHAT!?!





























If I could reach through this screen I would give you such a smack!








Do not pass go. Do not collect 200.00. Do not stop on the way home and buy anymore crack! 
Your injector o rings are shot. All of your problems are consistent with shot injector o rings. AND you should not be able to easily turn your injectors. THEY ARE TOAST. KAPUT. NADA. CRAPOLA. HONDIZED!








Don't be a weeny about pulling them. Grab the injector line and yank them out. Put new o rings on. Slide them back in place and enjoy the fact that your car works so well
Rant finished. Where's that lithium.....


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## rice (Jul 19, 2006)

rebuild your entire injector assembly.
do it right, or do it twice.
this means you have to replace the plastic injector cups, the injector cup o rings,and the upper and lower o-rings on the injectors.
and be careful to not bend the fuel line while removing or installing the injector
becareful when taking the injectors out because the lower metal tip on the injector can randomly fall off. it is a press fit, but 2 of my 4 just fell off, never to be found again...
you can take the metal tip off, but i wasnt able to pry them off.
which made the next task that much harder.
its not easy to shimmy the big green o-rings on because they do not strech at all! it took me lots of force to get them over the injector nozzle and the c clip. 
but after that, the rest is easy.


_Modified by rice at 6:53 PM 10-23-2007_


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## rice (Jul 19, 2006)

4 of each (might want to get 3 extra large o-rings incase they rip during install)
you probably wont need the brass cup holders
and dont bother with the injector puller, garbage unless you have an 8v
http://germanautoparts.com/Vol.../94/5
http://germanautoparts.com/Vol.../93/5

_Modified by rice at 6:51 PM 10-23-2007_


_Modified by rice at 7:06 PM 10-23-2007_


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## eltopo (Jun 20, 2007)

*Re: replacing injector O-rings*

Thanks to all who replied... anyway, I had already bought the injector puller and the CIS differential pressure regulator test harness before I saw Rice's reply:








Indeed, the puller is not fully useful on the Fox. You can use it on the first 3 injectors (from the front of the car) without any problems. The injector puller is not usable on the most difficult injector to get to (#4), because there is a sensor on the intake manifold which gets in the way. The puller worked great on the first two injectors. It didn't work on #3, though- the injector was stuck in extremely tightly.
My dad (who is the real VW expert in my family) gave me a lot of help and we eventually got #3 injector out with vice grips on the hex barrel fitting, and the careful application of excessive force. Fortunately, we did not damage any of the injectors while extracting them.
The tips of the injectors were still shiny, but there was a fair amount of dirt on the injector body:








One of the injectors seemed to have rust/corrostion on the stem, which I assume is from moisture leaking past the O-ring.
The old upper O-rings were completely shot, as you all predicted:








(I cut these in half to get them off, they weren't like this. However, the O-ring on the stuck injector did break apart as we pulled the injector out)
Everything cleaned up nicely with carb cleaner:








On the advice of a local shop specializing in VWs, I used the (slightly oversize, right?) green colored diesel injector O-rings:








and we figured out the secret to reinstalling the O-rings is to use a bit of Vaseline and a suitable diameter socket to press against:








After cleaning up the plastic injector inserts the injectors seated nicely:









I was stupid and didn't buy new lower O-rings, because the shop I went to convinced me that the upper ones are the source of all problems. But I obviously should have redone everything at once. On the bright side it will be easy to pull the injectors out again and re-do the lowers at a later date.

So far, I don't know if this has fixed my original problem. The car still runs and I haven't had the loss of power problem for a while. I'll have to drive the car for a few weeks and see if power loss reoccurs. If not, I'll assume that it's taken care of. Thanks again to everyone for your advice.
In any case, 18 years and 150,000 miles is too long to go without replacing those O-rings.


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## rice (Jul 19, 2006)

i am jealous.
i wish i had known about the bigger diesel o-rings.
should have gotten new lower o-rings, but at this point, i guess dont worry about it. if you ever have to remove the injectors again, put some new one on.
and you could have built your own dpr tester for free with connectors from a junkyard


_Modified by rice at 4:32 PM 10-30-2007_


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## PASHAT (Oct 23, 2006)

*Re: replacing injector O-rings (eltopo)*

Good job.
I hope now you realize why I was somewhat upset to find that you hadn't looked into the o rings after being directed in that direction.
I am not sure about using those larger o rings.....o rings have to fit right and buying bigger doesn't mean that they will fit better. 
Might be the beginning of the end. Good luck with the car.


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## chois (May 12, 2000)

That was good to do, but your problem sounds very consistent with a dying, or dead transfer fuel pump in the tank, which is now killing the main pump.
Look at those systems next if the problem recurrs.


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