Help a Fool - Engine Revs Up When Gentle but Dies Under Load

[Mars]

Hey guys. I'm fumbling my way through getting my 99 running right, and I've fought this little fucker a lot recently. I have it idling now, but it's doing some odd stuff.

Two main things:

1. I have been having an inconsistency in cylinder number 1. Often it sounds like it's missing, and I pull the plugs to see cylinder 1 is wet but is getting good and consistent spark. All other cylinders have good consistent spark as well, and their plugs are not wet (however are a little sooty from richness). Why might this be?

2. I am able to rev up the engine with a light touch to the throttle, but when I get into it harder it starts to get very raspy and sounds like a lot of missing. If I bury my foot, I can kill the engine. I assume this is a fuel problem. Pressure maybe? Too little? Is there such a thing as too much?

Note:
-I have checked all injectors, they spray a very fine mist with no "pissing"
-I have changed the cap and rotor multiple times with no appreciable change.

Your help is greatly appreciated. I am getting pretty close here, and it's been a journey...

Here is a video:

http://youtu.be/lgakLHFoLTA

[squaab99t]

Have you check the ignition timing? With that helix thread jack shaft it is easy to be out of range to allow adjustment in the slots. AKA one tooth off.
The other thing might be the fuel pickup screen. maybe stopped up. It is on the front end of the fuel pump in the tank.

[Jordan]

Sounds like the ignition is way too far advanced and when you accelerate it advances further because of the mechanical advance in the distributor.

[Mars]

Have you check the ignition timing? With that helix thread jack shaft it is easy to be out of range to allow adjustment in the slots. AKA one tooth off.
The other thing might be the fuel pickup screen. maybe stopped up. It is on the front end of the fuel pump in the tank.

I went and grabbed my manual to triple check my work. It's a little frustrating because they don't have an "installing the distributor" guide for the distributor I have. Only the AC Delco and Bosch points ones. Anyhow, I snapped 2 pics.

This is how the distributor was set (with engine at TDC) at the time of my original post. According to the manual, on the points distributors, the mark on the rim should be in line with the rotor. As you will see, it is not:



So, I pulled it out and reset it so the mark aligned with the rotor:




Then, I started it. At first the engine would barely fire, so I had to advance it some, then it started. It however is exhibiting the same symptoms as before.

Sounds like the ignition is way too far advanced and when you accelerate it advances further because of the mechanical advance in the distributor.

Building off of this, I disconnected the vacuum advance and plugged the line. No change. Is there also a mechanical advance inside the distributor?

[GOLFGURU]

Yes there is..Is it a djet? I would set the timing @ 1o deg. btc @ 800 rpm then rev it while aiming timing light to see if timing advances,2000rpm should be around 25*btdc I would also splice in a fuel preasure gauge at the rail, to make sure your getting 30lbs. of fuel preasure. Jegs has em for 20 bones..Make sure the gauge goes to 30lbs..Good luck,Joe I think also if your ignition condensor is bad,It has the same symptoms...

[99Super]

I think if the timing is set correctly and the injectors have good pattern, I'd lean towards a bad Control Pressure regulator causing a lean condition. Classic issue on K-Jet cars.

john

[Sean Tennis]

Mars, looking at the video this is on a cold engine... Your impulse contact switch is not firing the 5th injector (sometimes called the cold start injector) during warm up. Either a bad impulse switch, faulty thermal time switch or wiring issue.

The purpose of the impulse contact switch is to give added fuel to the engine via the 5th injector during warm up temperatures. A cold engine needs a richer mixture, more fuel or less air, this system uses more fuel. When the throttle is quickly opened the engine vacuum fires the impulse contact switch (little black plastic barrel with single vacuum hose and two electrical wires mounted to fuel filter bracket). If the thermal time switch (location-intake manifold at cylinder head between cyl 2-3) determines the engine temperature is cool enough the thermal time switch will allow the electrical signal generated by the impulse switch to travel to the 5th injector (location-top of throttle valve housing-has electrical connection and fuel line) and add an extra shot of fuel.

[Mars]

Thank you for that explanation. I wasn't sure exactly how that system worked. However, the previous owner set up the cold start injector to run at all times when plugged in, and at the time of taking the video, I had the injector plugged in. I can verify that it's working because when I unplug it, the engine will die.

I'm going to play with some things right now, and hopefully what you guys have suggested will help! Thanks.

[Mars]

I think if the timing is set correctly and the injectors have good pattern, I'd lean towards a bad Control Pressure regulator causing a lean condition. Classic issue on K-Jet cars.

john

Is the control pressure regulator the same thing as the warm up regulator?

[99Super]

I think if the timing is set correctly and the injectors have good pattern, I'd lean towards a bad Control Pressure regulator causing a lean condition. Classic issue on K-Jet cars.

john

Is the control pressure regulator the same thing as the warm up regulator?

Yes. The CPR regulates the fuel pressures used to control mixtures during the warm-up cycle and set the mixture when warm. If these pressures are too high (i.e., the regulator has failed completely or is clogged), then your air meter will not lift when you try to open the throttle and the car will die. If they are partially bad, the car will run (leanly) when warm, but is difficult to start and won't run cold. This is sometimes worked around by using the cold start valve to richen the system.
I'd go find an old VW guy and see if he has a fuel pressure gage setup he can throw on or let you borrow. I made my own and they are an absolute necessity on a CIS car.

http://www.mikegabriel.net/vw/badhabitr ... ssure.html

john

[rsp57]

sounds like fuel pressure to me

[Mars]

Well, I've called around to local shops and it doesn't look like anyone will lend out a gauge. I wouldn't mind putting together one myself but I'm not sure where to look and what to buy exactly. This car was so exciting at first but now I look at it sitting in the driveway and throw my hands up.

I've swapped cold start regulators, fuel pumps, and tried a million and one things with the ignition. I went to swap fuel distributors with the spare I have but it only has 3 of the 5 connections I need so that wouldn't work.

The fuel distributor makes some noise when its running. I don't know if that's right.

[Crazyswede]

Fuel pressure gages are quite inexpensive:

first result on google:
http://www.google.com/products/catalog? ... MBEPMCMAI#

How good is your coil? Have you checked your timing with a light yet? idle should be around 15 or 16 degrees BTDC iirc. I have had issues with low pressure in one fuel line causing it to run poorly on one cylinder. You could also do a compression check to rule out a head gasket issue.


Have you looked at the quality of your spark at each cylinder?

[Mars]

I went ahead and ordered this fuel pressure tester - http://www.amazon.com/gp/aw/d/B0006V2BI ... 177&sr=8-2

I hope it will connect without crazy fittings etc.

I have changed out the coil and battery as well as tested spark, all seems normal there. I have not used a timing light to set timing this far. I have only set static timing. That's another tool I don't have. If fuel pressure checks Out, I'll delve into that.

Additionally, I have checked compression. All numbers around 210 psi.

I'm such a noob...

[DrewP]

Go get a timing light, that should almost always be step 1 on any 'old' car.