# cis e fuel cut?



## euroboimk2 (Apr 12, 2010)

I've been having some issues with what I'm guessing is fuel cut. When I firts got my car (86 gti) it would act like I was hitting a rev limiter at 3000 rpm. It wouldn't go any higher that that when I punched it but yould go to about 5000 when I eased on to the gas. It only does this when I'm in gear however. When I'm in neutral or when the clutch is engaged it will red line no problem. I sprayed out the bottom part of the fuel distributer flap with brake cleaner and it temporaily fixed the problem but I have yet to red line the car while in gear. Now it is acting up again and I was wondering if anyone else is having this problem or what could cause it. I do need a new air filter pretty bad as mine seems to be oil soaked on the intake piping side of the fliter. Also, what are good filters for these cars? I was thinking a rechargeable k&n but would prefer to not spend that much on one.


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## Glegor (Mar 31, 2008)

check the timing. my car would only turn 3800 when i got it. it was still timed to the factory 6*. well, now its timed at 24* and you have a hard time keeping traction in second gear.

how old are your plugs/wires/cap/rotor? they need to be in very good shape. and ive bought brand new plug wires that ran like crap before.


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## WaterWheels (Aug 14, 2005)

euroboimk2 said:


> When I firts got my car (86 gti) it would act like I was hitting a rev limiter at 3000 rpm. It wouldn't go any higher that that when I punched it but yould go to about 5000 when I eased on to the gas. . . I sprayed out the bottom part of the fuel distributer flap with brake cleaner and it temporaily fixed the problem but . . . Now it is acting up again and I was wondering if anyone else is having this problem or what could cause it.


First is the K&N filter idea. If you want ot save a little over a long time in not having to buy replacement filters then OK, get one. If you think or have heard it is a performance improvement, save your money. But by all means get a filter as if it is all that dirty it is not helping things and could account for the 5000RPM limit you had as well as the other if it is so dirty. Replace the filter before doing any other tinkering.

Next to your problem. I can in no way imagine this to be ignition related as you state the problem. If the engine will raise to the limit with no counter force to hold it back then the ignition is doing its part. The knock sensor control box does have a vacuum connection for load sensing, but that only alters the rate of advance and peek RPM should still be able to be reached.

Picture just how the engine functions when you press the gas pedal. First that is a bad name as you do not control any gasoline, but rather the opening, throttle, for air to enter the engine. The fuel injection system does the fuel part. When you stomp on the pedal and open the throttle wide open air is allowed to enter the engine. The air sensor plate in this case lifts as it rushes past and that causes the fuel distributor to allow more fuel for a good mixture. So what can go wrong to cause it to go flat? First that filter. If the air can not get in fast enough to fill the void when the throttle is suddenly opened, engine goes flat (the filter is now doing the throttle bodies job). You indicate that the mixture unit and air tubes are covered with oil. What happens to oil when it gets cold, dirty or old? It gets thick and gummy. The air sensor and fuel distributor have to move freely to work right. If the oil is gumming things up and causing them to stick, again, they become the restriction instead of the throttles. Get these two things fixed and then see how things run. Not just spraying some cleaner in, remove, clean and check for movement by the manual.

Now I have to say a few things about this 24 degrees of static timing I keep seeing posted. This must be a wonder engine or something is broke and your making up for the fault. I'll explain:
VW watercooled 1.8L engines (8v) require about 34 degrees of total ignition advance to run good. Yeah, +/- a little depending on mass production, gasoline, modifications, etc. The knock sensor ignition control box applies up to 28 degrees of this total and the factory setting of 6 degrees fills in the rest. Now I can hear the question comming, "What about people who set their timing to 12 degrees advance . . ." The total really does not change as the control box only applies what is needed and all that is really changed is the response from a stand still (sort of speaking) or how fast the total is reached. Lets look at just what 24 degrees of static timing would mean:
1) Starting would become very hard or maybe not at all when hot. The mixture would be igniting way before the piston reached TDC. Very slow cranking would result and "kick-back" could happen which can cause damage. I built and ran some Weber setups with 14 - 16 degrees of initial advance and was borderline with starting. They also used vacuum/mechanical advance distributors with the total also at 34 - 36 degrees.
2) Loss of power would occur due to flame travel. If the ignition system were set with so much initial timing and still apply the 28 degrees you would be looking at about 52 degrees of total ignition timing. The peak pressure in the cylinders would be reached prior to the pistons reaching TDC and not just after as it should be. This would result in a loss of power at best and even damage if sever enough and left to continue.
If your engine is set and running OK with 24 degrees of intial ignition timing, that means the timing mark used to set the timing with a light would be 4.8cm from the dot instead of 12mm, I would suspect a mechanical problem. I would bet you or the prior did a clutch job and installed the flywheel wrong. That would account for your having to set the initial timing so far off for the engine to run right. Or you really do have a wonder engine, but I doubt that.


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## chois (May 12, 2000)

I run 32-34 degrees of static timing on my race car. Starts and runs fine. I do have the idle set up closer to 1200 though, and don't ever really drive it betwo 3750rpm.

I would do it in a pinch on a street car, if something were busted and I needed to drive the car, but variable timing is there for a reason folks - driveability.

I just disabled it on the race car because the knock box does add 'noise' to the timing curve. I just wanted to remove potential souces of variation.


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## GTIspirit (Dec 13, 2002)

euroboimk2 said:


> I've been having some issues with what I'm guessing is fuel cut. When I firts got my car (86 gti) it would act like I was hitting a rev limiter at 3000 rpm. It wouldn't go any higher that that when I punched it but yould go to about 5000 when I eased on to the gas. It only does this when I'm in gear however. *When I'm in neutral or when the clutch is engaged it will red line no problem.* I sprayed out the bottom part of the fuel distributer flap with brake cleaner and it temporaily fixed the problem but I have yet to red line the car while in gear. Now it is acting up again and I was wondering if anyone else is having this problem or what could cause it.


It takes very little throttle opening to redline an engine with no load, maybe 7-10% or so, so it's easy to understand how you can hit redline in neutral or with the clutch depressed.

Your comment that you can only reach maybe 3000rpm with full throttle and maybe 5000rpm by slowly depresseing the pedal makes it seem like there is some kind of interaction with the WOT switch, which would be tripped at full pedal but not if you slowly increased the pedal, until it is tripped at the end of pedal travel. This WOT switch is how the ECU knows to go open loop at full load, to a pre-determined DPR current value.

The CIS-E (KE-Jetronic) ECU does have a fuel cut rev limiter and it receives that rpm signal from the knock box, which in turn gets the rpm signal from the coil. But this wouldn't be related to the WOT switch. Maybe it's just a coincidence that your current rev limit is about half of what it should be, seems a bit strange.

As suggested, check the DPR current to make sure it's set correctly, according to the factory service manual, and that it hunts around a bit at idle which indicates closed loop operation.

Once you confirm that is ok I might suggest checking the fueling system, sounds like fuel delivery might be a problem as I can't think of what in the CIS-E would cause the problems you describe.

Good luck.

P.S. I'm curious, what's the Bosch part number on your KE-Jetronic brain?


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## Glegor (Mar 31, 2008)

my car starts good, and runs like a raped ape. and its timed WAY PAST the stock timing mark. its about an inch past the 6* mark. i run nothing but premium in it. it does not ping. it does not idle either. 900 is the lowest it will ever go. 800 if the headlights are on. maybe my knock box doesnt work? cause when it was at stock timing, my car would never touch the rev limiter. didnt have the balls to turn that many revs. im not positive im running 24* timing, just a rough estimate. theres only 2 timing marks on my wheel. 0* and 6*.. i know the consequences of too much timing, and how an engine will act if it is timed too much. i get 33.6 mpg, and my car cranks 3/4 of a turn to start wether its hot or cold. i know 24* is alot for a stock engine, but its not causing me any problems. something probably isnt working right. it is a gas VW after all. you cant expect these things to run like a diesel.. theres too many electronics to screw up. im about done with gassers for a while anyway. im having boost withdrawls.


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## chois (May 12, 2000)

From my experince the knock box does not ever 'add' timing. It always pulls timing, and simlpy changes the amount based on inputs and maps. When I disabled my knock box I had to crank a ton of advance to get to the low 30s.

I have seen some crossflow motors like to run 35 plus, but all the 8v I have worked with liked 29-33. In general the 16vs like less than the 8vs, and those knock boxes have less agressive curves in them.

EDIT - fwiw, my 'race' engine is basically just a good stock engine. Balanced, blueprinted, 1mm over bore, stock cam/head, good header, stock injection w/optimum AFR via fuel enrichment. I just don't ever use it at low rpm...


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## GTIspirit (Dec 13, 2002)

I expect the knock box ignition map might look something like this:









(Map is from page 40 of the V.A.G. Service ssp068 on the Scirocco GTX 16V.)

Though I'm not sure if these numbers are absolute relative to the zero mark or relative to the static offset. Since the VEZ has no way of knowing the absolute TDC then these numbers must be relative to the offset. But then maybe they assume the stock offset, which I think is like 6deg.


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