1.7 D-Jet

Engine was running just great until about two weeks ago, sigh. Now only fires on # 3 and # 4.

I have cleaned every connection including all grounds. And I mean cleaned them good! The elecrical appears to be just fine. I get a good noid light at both # 1 and # 2. The injectors have tested just fine as well (I'm getting about 7cc in 15 seconds). I have 40lbs of pressure the 1,2 rail. The spark plugs are getting juice and fire.

I have installed new points, cleaned the triggers (which shouldn't have mattered because of the sequence) and set the dwell. I'm a tad under at 44 degrees, but again shouldn't keep # 1 and # 2 from firing.

The timing has to be close as it runs really smooth for just two cylinders.

If I pull the power to injector 3 or 4, I get a real good drop and she will die. If I pull 1 or 2 - no change.

If I add propane to the intake, I get a good response in higher rpm.

I had originally traced to the Temp II sensor and it failed, so I replaced it. A new one seemed to be the fix, but only for a moment.

I have good fuel, spark and air -



I'm STYMIED (or just a REAL DIPSHIT)

Valves too tight????

I figured I'd try to get the valves adjusted next week to be sure, but don't see how all of the sudden two valves would go out that bad when everything was just "peachy" prior to this.

I suppose anything is possible at this point.

Thanks for the suggestion!

29.4 for fuel pressure.

Typo - it was 30 not 40.

Slight Hijack:

I am having almost exactly the same problem.

Would love to hear some suggestions on this.

Went through the wiring as well and checked for breaks. Nothing.

Could this be the FI Brain?

don't think it's the ECU as I have replaced with another with the exact same result!

Good to know but I am running out of ideas, as it sounds like you are too.

Try cleaning the trigger points again. Remove them and pull a piece of paper through them.

Are the plugs fouled? If it's getting the right amount of fuel flow at the injectors, you should be able to rule out the FI stuff. If it's getting good spark (you've tested plugs and wires?) then you should be able to rule out electrical stuff. All that leaves is air flow. Valves? Something blocking the intake? I'm not sure what else it could be...

Good luck!

The injectors fire in batches of 2 ( 1&4, 2&3) so it is not the points. Pull the injectors on that bank and check the spray pattern. It is possible that you have some crap that clogged those two injectors. They are getting juice as per your noid test.

You need:

Spark - checked it and it was good, what do the plugs look like? Dark and sooty?

Noid check - good

Fuel from the injectors - 7cc/15min, but how was the spray pattern? Big drops?

Fuel pressure - checked good at 30psi

Propane is useless unless you are checking around things. Putting propane into the intake will give you a boost no matter what.


Compression - How is this?

The injector wires are not on the wrong injectors are they? Swapped 1 and 2?

Plugs look really good. And the trigger points have been cleaned and recleaned.

I am leaning toward the valves, but just doesn't make sense to have TWO go at the same time when all was extremely well just prior.

Exasperating to say the least!

Sorry maybe a dumb question; what kind of paper are you referring too? Normal printer or 2000 wet sand paper???

- NOPE, THEY ARE CORRECT. For shits and grins even tried 4 different injectors last night. I spent over 5 hours going through everything again, and again and racking my brain

When I had a FI four we would use regular paper. You could see the black left behind on the white paper. I would not use sand paper on them.

Ya, valves, rings, and head studs are in the equation. Too bad the other, easier to fix stuff seems to be OK.

Used a match book cover and yes, wiped some black off and are real clean now. The trigger points fire apposed so this is been "cleared"

The only thing that is tied to both chambers are the head studs....but I am a pessimist. A compression check will show you what is up. The gauge is relatively cheap.

Compression test and valves are next on my to do list, but I am very doubtful that either will change the outcome.

I've been told by a very wise Porsche Guru that eventually it will all boil down to the basics, so I really hope to be proven wrong in my thinking and that the valves are the problem.

I would suspect the valves if they shared a common post that could be stripping out, but there are 2 separate posts for each bank of rockers. This is a puzzler.

If the FI trigger points were the problem wouldn't there be NO gas at the injectors????

I tested my injectors via the recommendations of Pbanders rennlist tech article. They were just like Dipshits.

Hmm. I would look at an electrical/signal problem. I had this same thing happen about 2 hours before heading to the WCR2009. Was final checking everything prior to my 380 mile trip, and my 1.7 started running like

Started trouble shooting and since I hadn't made any major changes I reverted back to wiring. Cleaned all the grounds, checked all the connectors at FI components........... and

The fact that you thought you fixed it with the Temp II sensor for a moment leads me back to this. If the ECU swap didnt fix it, the ECU is getting a bad/no signal from somewhere. Do you have another Temp II sensor? I may have one laying around for you. At this point I would probably check continuity on all the wires heading back to the ecu. One broken wire and no go.

Hope this helps,

Jim

I do have another Temp II sensor as I bought two. I tested both and no joy.

will advise all next week when I get back in to it.

Thanks for all the suggestions. Have a good weekend.

Mark

You are wasting your time if you have not set the valve adjustment correctly and verified that you did not loose a valve seat...(pounded into the head)

Tune ups on these motors start with setting the valves.
Then you set the points and verify that with a dwell meter...dont guess.
then you set the timing with a timing light...dont guess its right because it purrs...not a valid setting..

The valves and dwell cannot be off in the least or it will run wrong.
the timing can be off...it will run ok..it will behave poorly under load.

You have not answered any questions regarding the color of the plugs.
What plug brand and part number are you using?
How old are your plug wires?
Cap, Rotor, condensor, coil?

Most times the supposed FI issues are ignition related.

SET THE VALVES

Rich

Looking at the circuit diagram, everything we are talking about (except the distributor and spark wires) seems to connect through the wiring harness to the brain box.

From my computer days, connectors sometimes go intermittent as they (or the components) get warm....

Which brings up the questions, how are the connectors????

Have you checked the big assed connector that hooks up to the brain box? Do all the connections look like the others??? Any spread??

Hows about the connectors on the injectors???? Any look spread or different? You can usually pop the female connectors from the housing blocks with a tool such as the wire from a small paper clip.

Tried checking the injectors for performance when warm? From my solenoid design days, I learned that solenoids (aka injectors) warm up and the efficiency drops a lot. Which means that if a solenoid is marginal, it may have enough force to work when cold, but not enough to work when hot.

The other wierd problem thing that I have encountered is broken insulation on wires in the wiring harness. My daughters 1986 Volvo had the idiot tree hugger curse of biodegradable wiring..... Can you say a wiring harness filled with biodegraded insulation masquerading as non insulating insulation confetti pieces. The corroded bare wires randomly shorted together when the confetti shifted.....

On a previous car, I went nuts trying to sort out a simular problem. One of the shops that worked on the car previously, reversed the wires that go onto the coil; ( tach ground and pertronix at the time ). Takes just a minute to verify your condensor wire, tach wire, and ground are correct.

Here is the latest that I have done and I am STILL just running on # 3 and # 4:

Cleaned and Checked all Grounds

Replaced Temp Sensor II

Swapped out ECU

Swapped Wiring Harnmess

Cleaned points, contacts and set Dwell

Adjusted the timing

Adjusted the valves - now 110, 110, 100, 95 was 125 120 100 80

Swapped Dizzy Cap

Swapped Plug wires to test

Swapped Coil

Checked Fuel Pressure - 30 psi

Checked Flow/Spray of Injectors 7cc in 15 seconds, nice spray pattern

Still no joy with 1&2 and only running on # 3 and # 4

Are you confusing compression testing with valve adjustment? This line does not make sense as is.

What are your intake and exhaust valves set to?

Did you ever test the fuel spray pattern on your injectors?

How are you doing your compression test? A valve adjustment should not cause you to loose 15 psi in a cylinder, unless you are incorrectly adjusting your valves (too tight).

Zach

Check compression with the engine warm (if possible) and the throttle wide open. The difference between a warm and cool engine would explain the 15psi loss (assuming the engine was warm when you tested it last time, and cool this time.)

Also, are the "100" and "95" cylinders the #1 & #2 cylinders?

Do you have a leakdown tester?

So, just to confirm:
Your sparkplugs are known good, they are making spark, and they are not fouled.

You plug wires are known good.

You are getting fuel, and good spray from the injectors.

You are making compression - at least enough compression to run (you should be able to run @90 psi compression)

Your valves are correct.

Your timing is correct.

Your dwell is correct.


Really DUMB question, but are you positive that you have the #1 plug wire going to the #1 plug, and not the #2 plug?

Your dead cylinders have higher compression then your good cylinders?

If you are getting spark, air, compression and fuel - at the right time - it should fire.

One part of your equation has to be wrong... somewhere...

Zach

I agree, but to make it worse, sometimes when I get a cold start it will run on all 4 just as happy as a clam and then 1 & 2 will die again AND I CHECK THE INJECTORS WITH A NOID LIGHT AND THEY ARE GETTING JUICE.

for 1+2 not to run, it almost sounds like you are losing fuel supply to that side's fuel injectors. Are you sure the fuel lines are hooked up correctly and where are you taking the reading for fuel pressure? Could you have a couple of lines swapped? I bet when you find the cause, it will be something simple.
Tom

Fuel lines are hooked up correctly. The car was running beautifully prior to this. And had been running strong for two years. I got the pressure reading at the rail and the injectors tested fine.

Ya, I don't get it either.

SIGH.....

Sure haven't found anything obvious or simple yet !

Could you take pictures of your spark plugs and post them. I think that somehow #1&#2 are not sparking.

Also, is there any remote possibility that something (mouse nest / dead mice) is obstructing your exhaust where the 1&2 cylinders are collected? If they can't breath, they won't fire. If they don't fire, the plugs will foul. If the plugs foul, then you get no spark.

Its a wild assed guess, but we have seemed to have look at everything ahead of the engine, may as well look at things aft of the engine. Mice get into some really funky places, and a few people have reported shooting flaming mouse nests out the tail pipe.

Zach

Hey Mark, pull the trigger points connector from the distributor and check it very carefully for broken, cracked, or deteriorated wires and loose connectors. Could be an intermittent issue. I think Ben had problems at this connector at one point.

Ohm out the wiring harness from the ECU to the FI plugs and FI trigger points..

Most of the really wierd issues go back the old brittle wiring that finally broke.

Rich

This.

I just had a crank sensor die on my 01 GTi and it was causing intermittent running problems.

This was an 8 year old bosch sensor, not some 35+ year old wiring.

If I wiggled the wire while running a certain way it would die. The vibrations from starting out in 1st with my super heavy engine mounts would cause it to vibrate and fuck up the timing signal causing misfires and other nonsense.

It had been causing intermittent running issues for a while.

The second half of my problem was a weak coil that would mis at idle and changing loads, this is a 4 cyl coil on plug setup.

Swapped in my spare 4 coils, car runs better than ever.


Intermittent wiring/electrical problems are hard to detect.

Start wiggling wiring around and such while running.

Cold = contract
heat = expand

Hadn't touched her in several days until this afternoon at lunch. The temperature/pressure has changed here quite a bit since then.

Upon start up she fired on all 4 and ran real strong. I could pull #1, #2 injectors and get a drop, could pull #1, # 2 spark and get a drop.

Then as things warmed up or the PRESSURE dropped she went back to just running on #3 & # 4.

Will check fuel filter, pressure regulator next week and advise.

But I sure am pissed I can't drive her TODAY!!!!!!!

After everything I have done, I went back to the simple thought of "the only way that # 1 and # 2 won't fire is a ground problem" I believe stated by Dr. Evil.

That was EXACTLY what was going on. I previously just looked at the ground strap and it LOOKED good. However, when I actually pulled it off the car is was actually split and corroded under the washer.

I am back up and running and after the full tune of valves, dizzy, dwell and timing plus cleaning all the connections, am burning around town like a scalded cat!

Thanks to all

Actually I think it was Capn' Krusty that made the ground comment

Thanks Man!

Way To Go Mark!
Just in time for all the tourists here for Frontier Days.
Be careful out there...
Mike

Yep, tiz the season, look both ways at the One Ways!