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Alan L's Avatar
 
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diagnosis help

OK, I blew up a turbo when last on track. The internals let go and destroyed the housing. So it has a new turbo bolted on. Cranked it over after install, and all was fine.
The car has been parked on the trailer since, ready to go, but I haven't had time lately, so it has sat for about 6 mths. Went and cranked it over y/day just to fire it up and it is running rough. Pulled/cleaned plugs, still same. What is weird is the problem seems on one side of the engine. According to my heat monitor (bare hand), 4-6 are running fine, 1-3 are running, but much cooler. The engine also seems rich (AFR 10s). WP is 4.0 bar. It has a significant miss, altho all headers are too hot to touch after about 30 secs from cold at idle. But leave it 5 mins and the 1-3 are much cooler to touch than 4-6. It does sound like it is firing properly - on every 2nd cylinder. There is some oil in the IC intake, but none in the exit or butterfly throat. Dry. I guess that is expected when the turbo let go.
I have just done leakdowns on 1-3 and all are 2% (engine has about 5 hrs on new P/Cs and refurb heads).
So, summary is 1-3 seems to be down on power, rich AFRs, 1-3 leakdowns fine. I wondered if the cam timing could change - but hardly possible - right? And the leakdowns should be out if the cam timing has altered.
Stumped right now.
I am sure 6 mths ago it was ticking over just fine.
Have read somewhere here that White Spirits to flush IC of oil?
Thanks
Alan
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83 SC, 82 930 (track) - Stock except for RarlyL8 race headers, RarlyL8 Zork, K27-7006, 22/28 T bars, 007 Fuel head, short 3&4 gears, NGK AFR, Greddy EBC (on the slippery slope), Wevo engine mounts, ERP rear camber adjust and mono balls, Tarret front monoball camber adjust, Elgin cams, 38mm ported heads, 964 IC. 380rwhp @ 0.8bar Apart from above, bone stock:-)
Old 01-15-2019, 02:46 PM
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6 months can be a long time for gas to sit. Maybe its a combination of iffy gas and oil in the intake, or maybe it has gummed up the injectors or FD on that side for some reason?

Did you ever get it to full operating temp and did the miss remain?

Wouldn't it be rich if there is a miss, since the AFR reading is an average of all cylinders?

Maybe it just needs new gas and some techron run through it? I wouldn't change timing, fuel pressure or anything else that wouldn't change on its own until you are sure you have good fuel, no oil and no gumming of the FD head or injectors.

If that doesn't do it, confirm fuel flow through each injector is consistent?

good luck!
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Old 01-15-2019, 02:53 PM
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I did take it for a run down the road before doing the leakdowns. Have just done a leakdown on the other side to (#4) just in case. 2% also.
Yes - I am starting to head towards the fuel supply side. Pull injectors and check flows etc.
Regards
Alan
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83 SC, 82 930 (track) - Stock except for RarlyL8 race headers, RarlyL8 Zork, K27-7006, 22/28 T bars, 007 Fuel head, short 3&4 gears, NGK AFR, Greddy EBC (on the slippery slope), Wevo engine mounts, ERP rear camber adjust and mono balls, Tarret front monoball camber adjust, Elgin cams, 38mm ported heads, 964 IC. 380rwhp @ 0.8bar Apart from above, bone stock:-)
Old 01-15-2019, 03:18 PM
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cam timing wont show on leak down.
a compression could show a timing difference as compression is also based on intake valve closing. you would have to compare to right side.
I don't think cam timing is going to show up as a mixture issue. it might just idle rough

I would look at fuel next.
I would also consider just driving it and see if it clears up.


you are sure it was fine before it sat.
you did not pull any plug wires.
maybe you crossed 2 when you cleaned the plug, fixing one problem and adding a new one.

how did the plugs look when you pulled them.
no chance of anything from the turbo explosion getting in the engine.
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Old 01-16-2019, 03:53 AM
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Well the leakdown is done at TDC firing. If the timing has moved a valve may be partially open? But the leakdowns are good. But it is not a biggie to check the timing.
I was hoping it would clear driving it down the road too, but no luck. Not crossed wires (they are numbered, and I pulled the plugs to solve the already existing issue). It is one side of the engine that is not right.
The plugs are sooty black - all 6.
Can't imagine any turbo bits getting in the engine. We had all the bits. They would have to find their way past the IC. And it ran OK after a new turbo was fitted.
I think I have to check the timing first - can't see how it can change. Especially sitting in the shed.
But just have to keep eliminating options.
Thanks
Alan
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83 SC, 82 930 (track) - Stock except for RarlyL8 race headers, RarlyL8 Zork, K27-7006, 22/28 T bars, 007 Fuel head, short 3&4 gears, NGK AFR, Greddy EBC (on the slippery slope), Wevo engine mounts, ERP rear camber adjust and mono balls, Tarret front monoball camber adjust, Elgin cams, 38mm ported heads, 964 IC. 380rwhp @ 0.8bar Apart from above, bone stock:-)
Old 01-16-2019, 10:03 AM
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at TDC firing there should not be ANY valves even close to being open.
you are thinking of overlap.

you are running rich.
I know this is true for off idle like at cruise speeds but at idle the turbo could make it do the same thing.
if you have an air leak on the pressure side the turbo will actually require more air since it is blowing air out of the leak. in this case more air is pulled through the AFM increasing the mixture.
now my car always ran lean at idle with a pressure side leak but then I have a 7006 turbo. if you have a better turbo you could run rich at idle or if the idle is hi.

how does it drive. does it run and sound right driving.
reason I ask is if it is only an idle thing your plunger may not be dropping down all the way.
to check you can remove an injector and see if it is leaking with the pump on and engine off.
might be a good check anyway.

all plugs are black but one side runs better than the other.
I would compare fuel volume out of all 6, I know u have been through this.
I would do 2 checks. at simulated idle. takes about 15 minutes or more to get enough fuel to compare. connect a battery charger up while doing it.
the other is WOT.

air leaks at the ports. check the right side for air leaks.
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Old 01-16-2019, 10:31 AM
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I haven't run it on boost. So an air leak should be lean - right?
It is rich at idle and 2-3000 rpm. Never gets above about 10.5. Normally it would be 13-14 under light load at those revs. I guess I just have to plod my way thru til something shows up. What is weird tho is that everything was OK last I checked. But the engine makes an odd fluttering note. Like one cam is out. One side fires well, other side is trying, and not quite getting it right.
That is my best guess/analogy.
I will check cam timing (but I can't imagine how it could change) to eliminate. Just before the turbo let go the car just posted the best lap time ever for 10+ yrs on that track. So I think everything was pretty well in spec. If not cam timing, then fuel I guess.
Wondered if 1 pump has dropped out, but that doesn't explain RHS vs LHS.
Regards
Alan
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83 SC, 82 930 (track) - Stock except for RarlyL8 race headers, RarlyL8 Zork, K27-7006, 22/28 T bars, 007 Fuel head, short 3&4 gears, NGK AFR, Greddy EBC (on the slippery slope), Wevo engine mounts, ERP rear camber adjust and mono balls, Tarret front monoball camber adjust, Elgin cams, 38mm ported heads, 964 IC. 380rwhp @ 0.8bar Apart from above, bone stock:-)
Old 01-16-2019, 11:53 AM
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Funny how they often pull hard just before they break!

Now we always worry when an engine suddenly becomes more powerful with no explanation.
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Old 01-16-2019, 12:04 PM
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Yes - but usually because they run lean to the edge? They were always my most expensive karting laps.
But it wasn't lean - just a fresh engine and driven hard because I had a car on my bumper, lap after lap and wanting to have a crack at me. He got a windscreen full of failed turbo smoke instead (and he was the guy who had rebuilt the turbo) :-)
Alan
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83 SC, 82 930 (track) - Stock except for RarlyL8 race headers, RarlyL8 Zork, K27-7006, 22/28 T bars, 007 Fuel head, short 3&4 gears, NGK AFR, Greddy EBC (on the slippery slope), Wevo engine mounts, ERP rear camber adjust and mono balls, Tarret front monoball camber adjust, Elgin cams, 38mm ported heads, 964 IC. 380rwhp @ 0.8bar Apart from above, bone stock:-)
Old 01-16-2019, 01:07 PM
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Hi Allan,

Not much help with your engine issues, however as you would recall I had a lot of issues with my blown turbo and the amount of oil subsequent rebuilds pumped through the engine to the point of hydro locking it.

With my intercooler I was able to clean it by blocking the openings and pouring a good amount of methylated spirits into it and giving it a good rocking around. Then put it in the sun to dry.
Appeared to do the trick.

Steve.
Old 01-17-2019, 01:09 PM
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Weird crap going on there Alan. Go back to the facts: The only thing that happened to your previously well running 930 was a blown turbo....which of course pukes oil in to the intake. That oil would go straight into the cylinders and have no impact on your fuel delivery system (fuel head, distributor). You are still running with CIS, correct? Assuming you didn't foul a bunch of sparkplugs, which would make your AFR's read lean (due to unburned O2 in the exhaust emissions). And remember....I don't have to tell you this...that an air leak post-turbo compressor would show as a rich condition, being that some of the compressed air would escape to atmosphere. A pre-turbo compressor leak would show the opposite, drawing in unwanted/un-CIS-metered air. I just can't swallow that you suddenly developed a cam timing issue due to a simple turbo failure.
No real help here, just some thoughts.
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Old 01-17-2019, 02:37 PM
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the fluttering is probably from a cylinder that is too rich and is miss firing.

as I said, air leaks on these turbos can act different than you think.
I had my BOV vented to atmosphere and I had some strange this going on.

Idle was bad due to the BOV being open at idle and making it lean.
mid cruise, 2-4k was very very rich due the BOV being open BUT the turbo pressure was now BLOWING air out instead of the engine sucking air in. this pulled more air through the AFM making it rich, boost was normal because the BOV closed.

if you have a more efficient turbo on there instead of the 7006 its possible you are blowing air out at idle instead of sucking it in.
just a thought as to what would make u rich at idle.

another thing is the plunger.
check to see if you are leaking fuel out of the injectors with the pump on and engine off.
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Old 01-18-2019, 04:17 AM
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Is your NGK AFR Wideband fast so it reads misfires lean and not rich like some meters do? I would swap the plugs first. The WB might be oily too so some butane torch healing for it too.
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Old 01-18-2019, 04:47 AM
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Thanks guys. Not at the car right now. Will get back to it when I can. I guess I should be following the turbo trail. It did run OK after the install - had a 7006 on, but housing wrecked so had to fit a 7200. Fired it up after fitting 7200, just in the w/shop to check all was well. Idled away fine. Mark - I agree, cam thing weird stuff - just that that would be the nearest description I can give of the issue. And not many things will make one side of the engine run weird. I am thinking - change plugs.
Smurbus - maybe my WB is being fooled? But the plugs are soot black. I could try re tuning the idle AFR and see what happens. My gut feeling is it has to be some stupid s..t.
Thanks
Alan
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83 SC, 82 930 (track) - Stock except for RarlyL8 race headers, RarlyL8 Zork, K27-7006, 22/28 T bars, 007 Fuel head, short 3&4 gears, NGK AFR, Greddy EBC (on the slippery slope), Wevo engine mounts, ERP rear camber adjust and mono balls, Tarret front monoball camber adjust, Elgin cams, 38mm ported heads, 964 IC. 380rwhp @ 0.8bar Apart from above, bone stock:-)
Old 01-18-2019, 09:26 AM
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the left side could have always had some "issue" compared to the rt, but what ever is causing it to run very rich has made it stand out.

I had issues with the FD making strange things happen but you don't have the euro head on there.
could still be a fuel flow imbalance making the left worse than the right but I don't think I would let the left/rt issue distract you from "why are all 6 running rich", verified by black plugs.

the lft cam timing could be different but If it is I think it has always been that way.

just curious, have you verified both pumps run and system pressure
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88 BMW 325is 200K+ SOLD
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90 B2200[__] RUNNING:[] NOT RUNNING:__2000 MER E320 WAGON [] WRECKED:[]RUNNING:
Old 01-18-2019, 10:24 AM
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No, have not checked both pumps - wondered about that. Would it run rich? Not checked system pressure yet. Whatever has caused to LHS to run different I suspect has just occured - it has a strange systematic miss to it. Not a complete miss, a partial combust on every 2nd cylinder is my guess.
Regards
Alan
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83 SC, 82 930 (track) - Stock except for RarlyL8 race headers, RarlyL8 Zork, K27-7006, 22/28 T bars, 007 Fuel head, short 3&4 gears, NGK AFR, Greddy EBC (on the slippery slope), Wevo engine mounts, ERP rear camber adjust and mono balls, Tarret front monoball camber adjust, Elgin cams, 38mm ported heads, 964 IC. 380rwhp @ 0.8bar Apart from above, bone stock:-)
Old 01-18-2019, 03:15 PM
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OK - taken a while. Could not get back to the car until today. Checked cam timing.
Target value is 1.8mm.
The LHS (the one running cold(er)) is 1.75. The RHS is 1.85-1.9. Not ideal, but could not be responsible for this weird behaviour. Relief in one respect (don't have to re-time cams), and disappointing in that it really sounds/looks like a cam issue. One side of engine behaving different to other side. Looks like fuel system is next. Check Sys pressure. WP was in spec.
Regards
Alan
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83 SC, 82 930 (track) - Stock except for RarlyL8 race headers, RarlyL8 Zork, K27-7006, 22/28 T bars, 007 Fuel head, short 3&4 gears, NGK AFR, Greddy EBC (on the slippery slope), Wevo engine mounts, ERP rear camber adjust and mono balls, Tarret front monoball camber adjust, Elgin cams, 38mm ported heads, 964 IC. 380rwhp @ 0.8bar Apart from above, bone stock:-)
Old 02-03-2019, 07:28 PM
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As I understand the CSI system, low fuel pressure would equate to a rich situation, it's counter intuitive, but it seems to be how the CSI system works.

So I would isolate each pump electrically, then systematically take each one out of the fuel loop and see what changes (if any) occur.

Depending on your electrical set-up, it could be as simple as pulling each individual pump relay to isolate the pumps.

Best of luck!
Mark
Old 02-04-2019, 06:33 AM
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Quote:
Originally Posted by full quack View Post
As I understand the CSI system, low fuel pressure would equate to a rich situation, it's counter intuitive, but it seems to be how the CSI system works.

So I would isolate each pump electrically, then systematically take each one out of the fuel loop and see what changes (if any) occur.

Depending on your electrical set-up, it could be as simple as pulling each individual pump relay to isolate the pumps.

Best of luck!
Mark
Lowering Control Pressure reduces the force that must be overcome to move the piston in the fuel head, allowing it to move more exposes more "slit", which passes more fuel.

Yes, seems upside down
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Old 02-04-2019, 10:06 AM
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Right - so fuel pumps next. Maybe dropped a pump out. Then I will just plod my way thru - Sys pressure, injector flows etc. Something must show up.
Regards
Alan
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83 SC, 82 930 (track) - Stock except for RarlyL8 race headers, RarlyL8 Zork, K27-7006, 22/28 T bars, 007 Fuel head, short 3&4 gears, NGK AFR, Greddy EBC (on the slippery slope), Wevo engine mounts, ERP rear camber adjust and mono balls, Tarret front monoball camber adjust, Elgin cams, 38mm ported heads, 964 IC. 380rwhp @ 0.8bar Apart from above, bone stock:-)
Old 02-04-2019, 06:52 PM
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