CIS problem--help!?!
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Three Wheelin'
Joined: Jan 2007
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From: not where you think I am
CIS problem--help!?!
4.5L Euro CIS problem----
Symptoms are engine sounds as if one or two cylinders are not firing at idle. This continues up to about 2500-2800 rpms. Above that, engine clears up and pulls hard to redline. Gear selections do not alter this issue.
this is not a cold start issue.
aux air valve is working properly.
cod start injector working OK.
Warm up regulator inlet and outlet fuel lines/screens are clean.
Ignition system working properly.
New fuel fliter, fuel pump is OK.
all vacuum lines routed properly and are new.
intake gaskets and boots, throttle body seal and boot---all new.
I have not gone as far as checking the fuel distributor or injectors (yet).
Suggestions??? ideas??? Help-----
really would like to get this cleared up before 3rd Coast!
Thanks---Russ
Symptoms are engine sounds as if one or two cylinders are not firing at idle. This continues up to about 2500-2800 rpms. Above that, engine clears up and pulls hard to redline. Gear selections do not alter this issue.
this is not a cold start issue.
aux air valve is working properly.
cod start injector working OK.
Warm up regulator inlet and outlet fuel lines/screens are clean.
Ignition system working properly.
New fuel fliter, fuel pump is OK.
all vacuum lines routed properly and are new.
intake gaskets and boots, throttle body seal and boot---all new.
I have not gone as far as checking the fuel distributor or injectors (yet).
Suggestions??? ideas??? Help-----
really would like to get this cleared up before 3rd Coast!
Thanks---Russ
Thread Starter
Three Wheelin'
Joined: Jan 2007
Posts: 1,466
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From: not where you think I am
I was heading towards the fuel distributor next, but have no manuals or experience with it.
didn't even think of pulling the plug wires----too used to dealing with diesel engines where we just opened a fuel injector line to see which one wasn't firing---great suggestion---thanks!
--rhj
didn't even think of pulling the plug wires----too used to dealing with diesel engines where we just opened a fuel injector line to see which one wasn't firing---great suggestion---thanks!
--rhj
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Borat Impersonator
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Borat Impersonator
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From: St Augustine, FL
Usually a CIS fuel distributor needs to be rebuilt, I had mine done on the old Euro. It cost ~$450 iirc.
I used to have a PDF showing how to rebuilt it, but I was too scared to FUBAR mine. Lemme see if I can dig it up for you....
I used to have a PDF showing how to rebuilt it, but I was too scared to FUBAR mine. Lemme see if I can dig it up for you....
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From: Australia
I have had a misfire on one cylinder occasionally. Once isolated, I cracked open the connection to the injector to relieve pressure and the problem goes away - hasnt been back for a few years now anyway. My wrench said it was a sign of crud in the distributor blocking one outlet to an injector - rebuild time. I suggest you get the injectors properly cleaned (ie reverse flushed), and try again.
jp 83 Euro S AT 51k
jp 83 Euro S AT 51k
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Track Day
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From: Westfield,ma
if you need new injectors due to dirt make sure to inspect the inside of the gas tank where the fuel is returned. If the tank is full of black crud looking like coffee. You might need new rubber fuel lines from the body to the engine. I bought new injectors OE Bosch for 36.44 each or sent them to Witchhunter performance for reverse sonic cleaning and flow testing .. Witchhunter offered a great service for about half of new price for injectors.
Nordschleife Master
Joined: Jul 2003
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From: Minneapolis
You are jumping way ahead with the diagnosis. Missing is more likely spark and could be a vacuum leak. Bad spark often "smooths out" because the engine shakes better at lower frequencies.
Disconnecting the plugs is OK but check with a timing light as well. If it's sparking well and is tied to a cylinder then worry about the fuel distributor.
Toss is a bottle of Techron, Seafoam or your favorite FI system cleaner if it's not spark.
Disconnecting the plugs is OK but check with a timing light as well. If it's sparking well and is tied to a cylinder then worry about the fuel distributor.
Toss is a bottle of Techron, Seafoam or your favorite FI system cleaner if it's not spark.
Thread Starter
Three Wheelin'
Joined: Jan 2007
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From: not where you think I am
update:
checked cylinder firing by removing spark plug cables, one by one, while engine running. Found #5 and #8 did not alter engine smoothness (roughness). When removing spark cables from spark plug, you can "hear" the spark arcing from cable to plug, which leads me to believe that spark is not an issue.
Checked plugs in all 8 cylinders and found nothing unusual.
decided to go through the injection system, starting with the injectors.
removed injector lines, upon closer examination found that the holes in each end were crimped to very small openings, no two the same. using smaller, then progressively larger drill bits, I opened the holes up to a uniform size. I also did this for the lines going to the WUR, pressure regulator, and cold start injector. (it's an old trick we used for mechanical fuel injection diesel truck engines when doing a super tune up...)
removed injectors, then using a spray can of brake fluid with the little hose installed in the nozzle, I put the hose up into the injector while holding it upside down and caused the injector to "spray". Not good results. Only one injector had a proper spray pattern-- the others ranged from just dribbling fuel out to one ro two streams of fuel.
removed the fuel line banjo fittings from the fuel distributor. Did not find any screens under the banjo fittings. Sprayed cleaner into the openings.
returned injectors (to their original cylinder positions) and fuel lines, started engine and roughness had got better, but not great. Moved injector from #5 to #6 and problem has followed. Same for injector in #8.
At this point, I am headed towards injector replacement.
thanks for the help!
---------Russ
checked cylinder firing by removing spark plug cables, one by one, while engine running. Found #5 and #8 did not alter engine smoothness (roughness). When removing spark cables from spark plug, you can "hear" the spark arcing from cable to plug, which leads me to believe that spark is not an issue.
Checked plugs in all 8 cylinders and found nothing unusual.
decided to go through the injection system, starting with the injectors.
removed injector lines, upon closer examination found that the holes in each end were crimped to very small openings, no two the same. using smaller, then progressively larger drill bits, I opened the holes up to a uniform size. I also did this for the lines going to the WUR, pressure regulator, and cold start injector. (it's an old trick we used for mechanical fuel injection diesel truck engines when doing a super tune up...)
removed injectors, then using a spray can of brake fluid with the little hose installed in the nozzle, I put the hose up into the injector while holding it upside down and caused the injector to "spray". Not good results. Only one injector had a proper spray pattern-- the others ranged from just dribbling fuel out to one ro two streams of fuel.
removed the fuel line banjo fittings from the fuel distributor. Did not find any screens under the banjo fittings. Sprayed cleaner into the openings.
returned injectors (to their original cylinder positions) and fuel lines, started engine and roughness had got better, but not great. Moved injector from #5 to #6 and problem has followed. Same for injector in #8.
At this point, I am headed towards injector replacement.
thanks for the help!
---------Russ
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Sounds like you're on the right track.
Search around on the internet for replacement injectors. Those old mechanical injectors can be had pretty cheaply from some sources.
Search around on the internet for replacement injectors. Those old mechanical injectors can be had pretty cheaply from some sources.