WARNING! : DO NOT START WORKING ON YOUR FIP BEFORE YOU ACHIEVE THE BASIC SETUP FOR YOUR ENGINE : CORRECT VALVE CLEARANCE AND IGNITION TIMING AND LINKAGE SETUP !! THIS CANNOT BE STRESSED ENOUGH , OTHERWISE YOU ARE TRYING TO SOLVE ONE PROBLEM BY CREATING ANOTHER ,WHICH WILL DRIVE YOU CRAZY IN THE END ! !.
230SL bad engine running/starting mini tour Part 1 : the basics (
https://www.sl113.org/forums/index.php?topic=38391.msg280468#msg280468 )
230SL bad engine running/starting mini tour Part 2 : Air and Fuel supply (
https://www.sl113.org/forums/index.php?topic=38392.0 )
CSV :
The Cold Start Valve is part of the ( type III) starting aid system.
What's in a name ? It is designed to be electrically activated on EACH and EVERY start ! Not only during cold starts as the name may suggest ,just "starting valve" would be more appropriate .
Cold starts: CSV activated with a variable duration based on coolant temperarure ( below appr. 35 C /95 F ,sensed by TTS) between 1 sec.minimum and up to even 12 sec.for real cold conditions
Hot starts : CSV always activated for a fixed 1 sec. by the ,you might guess it, the small "1 second" relay
Fuel is delivered to the CSV by the electric fuelpump . System fuelpressure is measured at the CSV and should be between 0.8 and 1.1 Bar.
Inside the CSV is a springloaded cone style valve operated by the electrical relay. When the relay is energized it opens the valve and allows fuel to flow to both nozzles.
Common CSV problems:
-Starting problems ,hot or cold, due to no fuel spray
Can be caused by CSV relay failure itself or CSV relay not powered by starting aid (relays,TTS,etc.).
or due to clogging of meshfilter at inlet, inlet opening in tube to nozzles (often overlooked,see photo), or nozzles themselves.. The v-shape nozzleholder can be carefully removed ,(note its orientation !) for easier cleaning of the nozzles. A thin needle and a suitable solvent is all you need.
-Uneven (idle) running, rich running can be caused by a leaking valve. For a quick check remove the little hexbolt at the housing, have your el. pump running and see if there is fuel dripping out of the opening.
Small leaks (vapor) however may get visually undetected.
Another preferred way I used to detect a leak is loosening the complete CSV , turn it upside down, reconnect the fuelline , have the el.pump running , check for leaks at the nozzles.So far nothing new.
TIP 7 : a simple but effective trick : put a piece of tissue over the nozzles and check if it gets wet with fuel. This way I discovered my (still) leaking valve eventhough it looked OK at first.
The cone valve can be lapped in its seat by spinning, using a piece of hose for grip and some fine metal polish between the mating surfaces to obtain a good fit again. Clean it thoroughly afterwards!
* fuel supply ( high pressure )
Fuel under high pressure is supplied by the FIP pumpelements in order to
a) open the injector valve at the tip of the injector and
b) provide a good atomized fuel spray pattern.
The fuellines between FIP and injectors should always be completely filled with fuel and free of air, even with a non-running engine.This is achieved by "locking in " fuel between the valve at the injector tip and
the socalled checkvalve below the FIP outlet. Both of them need to close perfect to enable this. Even the slightest leak in either one will drain the fuelline and allows air to enter the fuelline after engine shutdown.
When you have air trapped in a fuelline at startup it may take quite a while for the FIP to refill the lines and operate the injectors again.It seems an eternity before your engine is running on all cylinders due to this temporary fuel starvation.
Important note : the activation of the CSV at startup may camouflage this problem. Your engine starts up on all cylinders very, very short ( due to extra fuel from the CSV entering via the manifold) then starts to sputter or stall again until the fuellines are completely filled up again. Thereafter your engine seems to run normal.This phenomenon is often confused with starting aid problems !
Conclusion : just a small leak in the high pressure part may be one of the main reasons for starting problems either warm,hot or cold !
INJECTORS (newer R2 type) :
TIP 8 : After removing an injector , screw in an (old) sparkplug a couple of turns They have the same thread and prevent debris falling in !.
The R2 type mechanical injectors are the improved version of the R1 type. Do not mix them !.
Their design is very simple : a fine mesh filter at the inlet and a springloaded valve at the tip ,opening when sufficient fuelpressure is supplied by the FIP.
No need to say that this filter needs to be clean. Cleaning of the filter can be done by "backflushing"
https://www.youtube.com/watch?v=RnegCu5-i9M https://www.youtube.com/watch?v=-kR1Lrmi5UwOpeningpressure of the valve should be between 15 and 18 bar.
I experienced difficult starting (on 5 cyl. initially) ,poor pickup ,uneven running at all rpm's ,hesitating ,lack of power ,couching, backfiring and the such.
Using the Colortune ( for description see previous Part2 )the malfunctioning cylinder was easy identified. There was a good spark ,so an ignition problem was ruled out. But at this single cylinder I observed an erratic combustion accompanied with erratic blue/orange flashes as well. Strange, so there must be a fuel related problem.
After removing the fuelline I did not see any residual fuel present in this injector opposed as to the other injectors ,a clear hint.
TIP 9 : As a first quick test the injector was taken out ,hooked up to my compressor air gun with a piece of hose and submerged the tip of the injector in a fluid. Bubbles appeared.... So definitely a leaking injector ! In my case caused by contamination or varnished fuel. That was the obvous reason for these problems :
a) poor starting at 5 cyl. due pressureloss in the fuelline,
b) erratic (rich) mixture in one cyl. ,as observed using the Colortune, causing uneven running and fouling the specific sparkplug
c) uncontrolled fuel leaking in the cylinder, causing combustion at the weirdest moments ,even at moments with intake or outflow valve maybe partly open and thus possibly disturbing intake airflow or dumping unburnt fuel in the exhaust causing the backfiring and not to forget : poor running.
TIP 10 : Now that the problem was identified I was on the brink of buying new injectors ,but instead I gave it a try to clean and restore them. I was able to clean and rescue all my injectors using the simple technique using a no-weld homemade poptester as mentioned in my other posts :
https://www.sl113.org/forums/index.php?topic=37588.msg274764#msg274764 (injector rescue)
https://www.sl113.org/forums/index.php?topic=37588.msg277164#msg277164 ( homemade no-weld poptester)
https://www.sl113.org/forums/index.php?topic=37588.msg277165#msg277165 ( more photo's poptester)
Another warning : A leaking injector ( or bad spraypattern ,i.e. small jets) may also wash away the oilfilm between cylinderwall and pistonring, causing extra cylinderwear, as well as dilluting your engine oil and thus reducing its lubricating ability ! !.Potential engine damage looms around the corner....
After cleaning my injectors I corrected my mixture and idle settings ,now with a stable running engine and all my running problems were solved.
FIP checkvalves :
As mentioned above the checkvalves prevent draining of the fuellines.
2 types were used : cone style (earlier version) or the improved ball style ( not discussed here).
First a simple leakcheck : remove the fuellines from the pump and blow out some residual fuel from the outlet fittings .Press and keep the fuel control rack to its stop and run the electric fuelpump a few minutes.If you observe a rise in fuel level in the outletfitting ,or even overflowing, you most likely have a leaking checkvalve.
If a leaking cone style checkvalve is suspected you might try to lap it to clean and/or obtain a proper closing again. The checkvalve needs to be removed from the FIP.This can be done leaving the FIP in the car.Clean the exterior of the FIP around the outlet fittings first ! Use a simple homemade tool with M12 x 1.0 thread to pull the checkvalve out. The conevalve can be lapped in its seat by spinning, using a piece of hose for grip and some fine metal polish between the mating surfaces to obtain a good fit again. Clean it thoroughly afterwards! Check the seals and replace them if necessary. Important : install the outletunions with the prescribed torque !
https://www.sl113.org/forums/index.php?topic=31302.msg260494#msg260494 (DIY checkvalve removal tools)
https://www.sl113.org/forums/index.php?topic=15754.0 (DIY checkvalve removal tool and installation discussion)
If you observe anything incorrect in my text please PM me so I can adjust it.
To be continued with Part 4.....
