Dumping raw fuel into exhaust (left bank)

You've been around a while so you already know this...
first of all DON'T RUN or DRIVE IT.
Get it outside, if burn the house down your wife is going to kill you and then all we'll have is you dead and a burned up car.
Do you have the Bosch injection shop book?

 

If it is running "ok" and not on just 6 cyln, then we know it is a FI problem.

Check the FI electric wires to that side and make sure some little wire didn't break or fall off one of the switches on the fuel distributor.

 

Aaron,

I can't remember so check the owners manual.
Are there 2 relays (1 for each side) that control the fuel distributors on the relay board?
If so, swap them and see what happens.

 

Your 400i being K-Jet without Lambda, there are very few "electrical" things that could go wrong. In fact, the only one that I can think of is if a cold start injector is wrongly staying energized so the 1st thing would be to just unplug them after you've got the engine running. It's also possible that a cold start injector could be physically stuck open -- the test here would be to "jump" the fuel pump relay sockets so the fuel pumps are running and to see if fuel is leaking out from the end of the (removed) cold start injector (although be prepared that fuel might squirt out).

You might also check/compare the physical movement of the air flow metering plates when the system fuel pressure is zero -- let it sit overnight and crack open the fuel connection to the cold start injector (or some other convenient place on each bank) to confirm it is really at zero pressure (just be prepared that some fuel might squirt out -- i.e., be ready to immediately wrap the connection in a rag before loosening). If you've got a stuck plunger inside one of the fuel distributors you should be able to tell the difference in the "feel" of deflection and return of the airflow metering plate.

Beyond that you really need the K/KE-Jet pressure gauge test set-up to check the supply pressure and the control pressures coming from the warm-um regulators.

Have you looked at the spark plugs to see if the whole bank is running rich or just 1 cylinder?

 

You may also play with the by-pass adjustment screw. It is a approx. 1/2" diameter spring loaded adjustment screw. I had a similar problem, and kept on playing with the one on my right hand bank, and the white smoke and gas smell went away.

400 gts

 

Aaron, did you solve your problem?

I tried to start our 400i yesterday after about 6 months... I got the identical problem as Aaron, except the white smoke was actually vaporized fuel! I checked the plug wires with a timing light and I've got spark on both banks (and obviously fuel). Right exhaust tips are hot, left cold. Ours has some kind of add on box (probably for gray market certification) with an O2 sensor and what looks like an injector in an added feedback/bypass line on the left fuel distributor. I pulled the fuse from that box and it seemed to want to fire better on the left bank. It could be coincidence and the cold start enrichment had shut off by then. I quit because by then I had a gas puddle forming under the left tips, running out the garage and I didn't want to test the big bang theory... I pushed the car outside to dry out the exhaust overnight before I try again.

I assume if I unplug the cold start enrichment, it won't add more fuel... I shouldn't need cold enrichment to start over 65 degrees anyway... I may try that later today.

If these things had a sophisticated ECU I'd say there was a timed virus in it. In the case of CIS, that's like saying my abbacus had a disc crash.

 

The add-on box with the "frequency valve" is an emissions related device. It is designed to alter upper and lower Fuel distributor chamber pressures in response to the O2 sensor voltage. Should be one for each bank, although not all cars got them and not all cars still have them.

The normal function is to hear a "buzz" from the frequency valve (the solenoid you speak of) when the engine is running with proper power and "duty cycle" supplied by the add-on box. This is low-tech stuff and if the frequency valve is not functioning, the car will run extremely rich and duplicate your symptoms.

Early US 4V 308/Mondial's had this same system and the power control relay for the ECU and the frequency valve is under the metal panel under the carpet on the right side of the trunk. Often, it would get wet and the fuse on top of the power relay would go bad. Then the car would run badly.

Aaron, I'm in love with your car and would buy it without hesitation (partially because I think I know how to fix it easy enough before the drive home ) if, if, if...

Good luck.

-Peter (closet 400i fan)

 

Ours only has the add-on on the left bank. I'm sure that works real well... Will pulling the fuse disable it or should I remove the related fuel lines too?

After reading the Bosch K Jetronic page again, looks like disconnecting the Warm-up-Regulator electrical for debug will just leave the mixture rich forever... Plugging the warm-up vacuum lines or disconnecting the Cold Start Injector is probably a better idea...

 

After airing out the exhaust for ~24 hours I started the 400i again today. In ~30 secs the plugs cleared and the engine was running on all 12, after about 5 minutes the left bank stopped smoking, probably after the pipes/mufflers dried out... Standing behind, in the center there is stereo "music" again. The fuse for the "add on box" will be replaced with a dummy... and the wife is happy that her 400i is back in the garage again.

Thanks Peter for the explanation of what the box does.

 

Currently trying to determine what makes the mixture too rich. I have bought the Probst book, an excellent book. I suspect whether the Warm-up regulator or the Cold start injector.

I have disconnected the Wur and saw no result. The reason could be that the engine was warm, so the bimetal spring does its job, to inrease the counter pressure, whatever the electric connection.

Now, I'm back home and I keep on thinking about it.
My question is : what if I disconnect now the Cold Start Injectors ?

The engine cold starts perfectly, revs perfectly as well, but 20 minutes later, the rev is not so easy, the engine lacks of power and smells fuel, which makes me think the mixture is too rich. If anyone has ever experienced a situation where the mixture is too rich, feel free to share.

Thanks in advance,

Olivier

 

Hi again, I feel like I should have searched a bit more. This contribution answers my last question. Apologises. Maybe one of the CSI is stuck open or wrongly stays energized.

I was said by a vw collector that the CSI is similar to the one that can be found on a VW GOLF GTI (generation one and two) and its cost is in the 100 us $ range.

Olivier

 

I have kept on enquiring on this disorder : the cold engine starts fine, then as the engine gets warm, it does not rev as well. I had the car serviced by a Bosch workshop with no result.
I recently met a skilled and nice guy who collects k-injected gti rabbits. I showed him the car, the probst book and told him what I learnt from the forum and especially the enrichment processes.

His advice was : it smells gas.So:1check the wur 2 the csi. When leaving he added: by the way, did you check the sparking plugs?
Next day, I disconnected the wur, then the csi, no improvement. Then I remembered his last words and I used a light to look at the sparking plugs : one was jiggling, I fixed it and it did the trick, now the engine runs perfect.
A big thanks to the fchatters whose skilled contributions helped a lot to apprehend the bosch injection and its potential troubles. Olivier