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Alan L's Avatar
 
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CIS injection sequence

I think this is a dumb question, and I think I know the answer.
But I'm struggling with a problem and looking at any options/opinions.
I had the top half of my engine apart - dealing with boost leaks- new injector blocks/gaskets/seals etc.
Got rid of nearly all leaks at present - but the engine is running like a bag of farts. Basically running on the LHS three, and nothing on the RHS 3.
I don't believe there is any injection sequence timing on CIS, having had the unit apart previously. But it is possible I crossed two of the injection lines over on the RHS, where they hook into the fuel head - but I can't see this would actually make a difference to anything? Am I wrong?
After 'idling ' -as best you can on 3, for about 30 secs, the headers on LHS are too hot to touch. The headers on RHS are stone cold, with one luke warm.
Alan
Old 04-24-2008, 09:26 PM
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Brando
 
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No sequence. CIS is "constant injection system" if I'm not wrong. This means that all injectors are designed to get the same amount of fuel at the same time. Not so tuner friendly But dependable and relativley simple. In your case, either the fuel head would have a blockage or the injectors on that side all have some blockage. Stephan at imagine auto could chime in here and fix all my faults if any. You can test them w/ a glass to inspect the atomization or spray of each injector individually.
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Old 04-24-2008, 11:18 PM
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I don't believe there is a blockage - I have just calibrated the injector flows.
I wonder about spark - but there is spark at these faulty cylinders, and timing is OK (the other 3 seem to be doing fine ignition and timing wise).
Very frustrating - but it seems it can't be due to any crossed injector lines.
It runs for about 10-15 secs at 'idle' then dies. The RHS seems to come in intermittently - sometimes #4, or 5 or 6. occaisionally two at a time, but never 3.
But always dies after about 15 sec.
Any throttle and it coughs and dies straight away.
Grrh.
Alan
Old 04-24-2008, 11:59 PM
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Double and triple check plug wire routing. Had one once where the tech manual had a miss print on the direction of rotation of the dizzy. Car ran good on three cyl.
Old 04-25-2008, 04:31 AM
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Crotchety Old Bastard
 
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Could your cam timing have jumped off line on the RHS?
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Old 04-25-2008, 05:31 AM
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Simple test on timing, hook a inductive timing light on each of the wires on the bad side and see if it operates the light, if so then at least the wires/distributor is sending spark to the plug.
Pull the plugs and see if they smell like gasoline,, then you know you are getting fuel to the cylinder.
If so, then the problem becomes more involved in checking the actual timing sequence of the cylinders, checking if cam timing is off, etc.
I found the best way of finding a problem is going step by step thru each system, eliminating one thing at a time. Start out easy and then go bigger, and overlook nothing, something stupid like a faulty distributor cap could be the issue.
Let us know.
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Old 04-25-2008, 08:22 AM
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Thanks guys - it has to be a dumb sh...t problem. Just matter of nailing it.
Cam timing should not have jumped - will check simpler things first. Since I had all the manifold etc off, I wonder about the RHS not seating properly. In spite of pressure testing it originally when manifold back on, before intercooler etc fitted, I am inclined to strip it back to the manifold again, and reassemble again.
The plugs always have fuel on them, and I have had the leads off with a plug in each of them, and watched them sparking. Also fitted new plugs. No difference. I think it has to be fuel (or fuel/air).
Will keep you posted.
Regards
Alan
Old 04-26-2008, 11:39 AM
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Sure sounds like cam timing. Not jumped or actually slipped, but mis-timed. Let us know what you find, we love mysteries!
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---Les Garten---85 930, Andial IC, GHL Headers, Fabspeed Dual, K-27 HF2, 3.4 JE Full Finned 7.5:1 CR, 964 CAM'd, Carerra 3.2 Manifold Cut/Flipped, Tec3r, Siemans 55#, GSF Fuel Rails, Clewett Crank Trigger, Clewett Cam Trigger,Dual Plugged, ARP Head Studs/Rod Bolts, Clewett Wires.Tial 46mm WG, Tial 50mm BOV, WEVO Shifter,934 Boost Gauge, Wideband EGO Sensor/Gauge, C2T Head Gaskets, '88 MB 300TE,BMW R100RT
Old 04-26-2008, 02:24 PM
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Could be cam timing, but if it's not running on the three cylinders, the timing would have to be way off, like it skipped a tooth or two.
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Old 04-27-2008, 04:36 AM
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Quote:
Originally Posted by 78 STROSEK View Post
Double and triple check plug wire routing.
+1
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Old 04-27-2008, 05:48 AM
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Quote:
Originally Posted by 125shifter View Post
Could be cam timing, but if it's not running on the three cylinders, the timing would have to be way off, like it skipped a tooth or two.
Or a perfect 180 degrees.
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Old 04-27-2008, 09:21 AM
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Except I have not touched the cam timing - I've just had everything off down to the long block.
Will keep you posted - hope to get the manifold hardware off again tonight.
But I agree the misfire sounds like cam, and my neighbour who heard it running immediately suggested cam. But I have not touched them, and it would be unlikely to jump under these conditions? It has the carrera upgrade tensioner on the '82 block.
Alan
Old 04-27-2008, 01:11 PM
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Quote:
Originally Posted by Alan L View Post
Except I have not touched the cam timing - I've just had everything off down to the long block.
Will keep you posted - hope to get the manifold hardware off again tonight.
But I agree the misfire sounds like cam, and my neighbour who heard it running immediately suggested cam. But I have not touched them, and it would be unlikely to jump under these conditions? It has the carrera upgrade tensioner on the '82 block.
Alan
Hi,
I guess I mis understood when you said," I had the top half of my engine apart".
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---Les Garten---85 930, Andial IC, GHL Headers, Fabspeed Dual, K-27 HF2, 3.4 JE Full Finned 7.5:1 CR, 964 CAM'd, Carerra 3.2 Manifold Cut/Flipped, Tec3r, Siemans 55#, GSF Fuel Rails, Clewett Crank Trigger, Clewett Cam Trigger,Dual Plugged, ARP Head Studs/Rod Bolts, Clewett Wires.Tial 46mm WG, Tial 50mm BOV, WEVO Shifter,934 Boost Gauge, Wideband EGO Sensor/Gauge, C2T Head Gaskets, '88 MB 300TE,BMW R100RT
Old 04-27-2008, 03:56 PM
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We are making progress - I can report, after extensively leak testing the manifold again, that it is a fuel problem.
One I have not struck before. There is erratic fuel pressure, it starts out OK, briefly, then falters, then the pumps are left whining, but nothing comes thru. This explains the engines brave attemp to start at first fire, then coughs and lumps along getting progressivley worse until it expires. The RHS seems to falter worse/earlier, but I can't explain why - but both sides of fuel delivery finally fail.
Wait a minute, try again - instant pressure/fuel at injectors, only to erratically fail on 4-6, then a few seconds later 1-3. Pumps still whining.
I know - has it got any fuel? I just put 30 litres in it, the gauge reads just under 1/2.
But it has all the symptoms of running out of fuel. Which it is - except it has plenty.
Ideas?
I'll post this as a separate Q now I know what we are looking for.
Thanks for ideas, fortunately I can leave the cam for now.
I can also report I do not believe you can statically pressure test intake system. Leaks at butterfly spindle, idle screw and the aluminium Y piece PUSHED into the manifold block.
Alan
Old 04-28-2008, 01:06 AM
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fuel

you need to pull inlet fuel hose off front pump and let it flow into container.for at least 15 seconds.should have good flow or problem..sounds like inside tank problem
Old 04-28-2008, 06:40 AM
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Pull the strainer out of the bottom of the fuel tank by unscrewing that big allen headed plug. Drain/siphon out the tank first or you will take a bath in gas. Check the screen element on this for blockage/debris and also try to look around inside the tank if you can thru the hole.
Also pull the fuel filter and replace it. These are 2 places to start. Then replace the fuel pump relays, since you have 2 and make sure both pumps are getting powered. If this don't fix it then maybe one or both pumps are going bad.
I have had a fuel pump still working but low on pressure/flow which iflicted my 911SC and it would idle but not run under load until replaced the pump.
Good luck.
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1979 930 Turbo....3.4L, 7.5to1 comp, SC cams, B&B intercooler, Snow Perf water/meth injection, Rarlyl8 headers, Garret GTX turbo, 36mm ported intakes, Innovate Auxbox/LM-1, custom Manually Adjustable wastegate housing (0.8-1.1bar),--running 0.7bar max
---"When you're racing it's life! Anything else either before or after, is just waiting"
Old 04-28-2008, 07:41 AM
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Interesting that it seems to "affect" one bank more than the other? If you had fuel rails I could see that. Was your car parked for a "long" time? How about damage from a jack pad under the car. I'm not sure if that is a possibility because those lines are pretty well protected for fuel. It sounds like you are never seeing good fuel pressure if your pumps "keep" running. We love mysteries here, keep us posted.

Les
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Old 04-28-2008, 08:26 AM
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OK guys, into the fuel tank we go. I had catch bottles under all 6 injector outlets, and there was definitely more fuel in total going to the LHS - but after about 15 sec it too would fail.
If we are talking low erratic fuel pressures, perhaps any weird thing would determine the path of least resistance, which would bias the delivery. At constant even pressure, all would be the same. But everytime I checked, the headers on 1-3 were always too hot to touch, and 4-6 cold, or one or two erratically warm. This is exactly what the fuel deliveries are doing.
Unfortunately, I've just put 30 litres in the tank to ensure not low on fuel. I've been working on it since Nov trying to get it up and running, so only carried minimum of fuel in it at any time. It may have run out of fuel just prior to this episode - but it should self prime at the pumps?
Regards
Alan
Old 04-28-2008, 11:12 AM
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Check fuel delivery to CIS first.

1. Is fuel filter saturated? (if not changed for a long time, change)
2. Both fuel pumps working/buzzing?
3. Remove fuel plumbing from pump/injection/tank, blow them clean with compressed air.
4. Check both pumps by measuring flow during 30 second run.

If part above checks out, it's time to troubleshoot the CIS. Start with measuring system- and control-pressure.
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Old 04-28-2008, 12:24 PM
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Problem solved.
Told you it had to be a dumb sh..t thing.
Was trying to run on rear fuel pump only.
This explains why it was getting a short dump of low pressure fuel, then cutting out.
The fault was the relay contact on front pump.
Grrh. Spent hours on ignition, boost leaks etc.
Underway now.
Thanks
Alan
Old 04-28-2008, 12:47 PM
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