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Runs on 2-3 cylinders when cold starting

smncutler

Member
Joined
Feb 5, 2012
This isn't really a problem, I'm just curious why it's happening. Every time I cold start my 83 245 with VX cam, it only runs on 2-3 cylinders and wants to die, as if it's running out of gas. I give it enough gas not to die and it runs smoothly after 10-15 seconds. When hot, it usually starts so quickly that I can only blip the starter or it will grind. What gives?

EDIT: I should mention it has new fuel pumps and filter, and no IAC valve.
 
I had misfires 3 or 4 times on my 240 in the last year. Twice it was loose spark plug tips, once it was poor injector connection, the worst was blown head gasket causing water in the cylinders causing cold start misses.
 
Thanks y'all. I have lots of new seals and new injector O-rings. Will check spark plugs for coolant.
 
might be low vacuum

Check your vacuum while the symptom is present.
If it's below 12" of vacuum, you'll get enough additional pressure through the fuel pressure regulator and to the injectors to cause the throttle stop fuel map to run rich enough to misfire.
If you have this condition, keeping your foot on the pedal once it's started and running it at ~2000rpm for the first minute may likely help increase the vacuum at idle such that it'll regulate fuel properly and not misfire.
Solution then would be more vacuum at idle or an adjustable FPR.
The 10-15 seconds elapsing and fixing your smoothness issue is possibly enough time in your car to build sufficient vacuum. It takes a bit longer than that in my n/a car with the RSI cam.
 
no it's not the cam, a VX cam is nothing special it's just a streetcam. Your engine should idle perfectly stable.
most euro B230FB engines got the VX3 cam as standard (130hp), (VX3 = VX but 3 degrees advanced if i remember correctly)

i would have a look at the sparkplugs and maybe do a compression test on all cilinders, that should tell you if you have a blown HG.
I have seen blown HG's that have blown between cil 2 and cil 3 the effect is low compression on 2 and 3 but no coolant leak, no oil contamination, but low on power and weird idle
 
The least intrusive thing to try is quickly unplugging injectors one by one to determine which cylinders are misfiring consistently or they all do at random. That should give some ideas about what's happening. Follow that with intake vacuum, compression checks, plug inspection, etc. How are the cap and rotor?
 
^^^^

Yes! Good advice. Do a cylinder drop test as mentioned above. Very fast and easy on these engines. That is how I found my poor electrical connection at the injector.
 
>Rented a compression tester from O'Reilly
>It was junk
>They gave me a brand new one
>It pissed air from the ****ty quick disconnect fitting (or I have no head gasket left)
>Plugs are fine
>Brownish coolant
 
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My injector wiring is fine, I'm doing an ongoing engine bay reverse wire tuck. I chopped lots of wiring out and just soldered all the injector connections. If I let off the gas to do a cylinder drop test while the symptom is present it will just die. I might not understand? The VX was a stock cam in Europe, but I bet it came with different maps from the factory than my M. In case it's relevant - my VX is advanced 2.5 degrees on a stock engine with 400k miles on it, and my valve clearances are too tight.
 
I spent an hour or two today dealing with misfires on a 2001 ford mustang GT 4.6L V8.

It came in with codes for misfires on 4 and 8; the rear cylinders of each bank. I am training to detect bad ignition coils with a scope. It is proving to be difficult. I am trying to minimize parts darts; it wastes time and money. However, my experiment was inconclusive.

So what does this have to do with your car? You can ohm out each injector and make sure they are similar. Also pull each plug and measure the gap.

Cylinder drop test: unplug each injector one at a time and see if there is a change in idle. Also get used to putting your hand over the tail pipe and feeling for a misfire. Also get used to putting your hand on the body and feeling for a misfire.
 
Sorry for the out of context, and hard to follow posts, but it's the best I can do currently barside!

So with the Rustang, I tried swapping coils around to see if the misfire would follow the coil swap. It didn't. Misfire codes started showing up for other holes and also the P0300 random miss. I kept pulling plugs and coils and found coolant and rust on some holes. From coolant leaks I have now fixed. Wire brushed off the rusty plug tips, checked plug gaps, checked for carbon tracking white chalky marks, etc.

After blowing out coolant fouled holes, wire brushing rusty plug tips and coil tips, reseating coil and injector terminals, I got the Rustang to at least be driveable and got a lot of power back.

Used mode $6 to try to keep an eye on the misfire counters, but it also kept changing holes. This is where parts darts might be warranted. I'm gonna throw 8 plugs and 8 coils at it.
 
I've been shortening and rerouting wires one at a time, solder, heat shrink, the whole deal. No changes in circuits, I color code and have my manual schematics bookmarked. Sorry for the confusion. If anything the wiring is better than when I got the car - the loom running under the front of the engine to the alternator was full of goopy oily melted wiring insulation. I even replaced all the engine ground straps, for heck's sake
 
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