83 245 b23f m46 misfire at 3500rpm idles "ok" new plugs, wires, cap/rotor a couple months ago
installed some junkyard injectors adjusted timing and there was no change
im at a loss i dont know what else to change!!
any help would be great

 

Sounds like your fuel mixture (%CO) is out of adjustment given all else is ok. When was the last time you changed you fuel filter? Did you replace the o-rings on injectors? Vacuum leaks can create problems too.

 

check your fuel pressure? should be 42-44 PSI above manifold and it should be able to maintain that at any RPMs and fuel consumption rate.

 

i installed new o-rings with the injectors fuel filter was done a couple months ago also replaced leaking vac lines im running out of ideas

 

injectors came out a 86 b230f they looked different but the performance seems to be the same

 

wait, isn't a 83 a K-Jet car? 86 is LH 2.x for sure

 

yea the injectors have the same psi though and it works so im gonna keep em in there the cap and rotor are a bit charred so im gonna replace today fingers crossed!

 

other way around my 83 has the LH and the 86 had k

 

um, K-jet (CIS, sometimes called 'mechanical') was used *before* LH (EIS). 83 might have been the first year for LH

 

"ooh all right well mine says LH on the computer 83 was the first year of the b23 so that may have been the change my injectors were yellow and the 86 injectors were blue and the "nozzle" was a bit different i did adjust my distributor a little bit to get the car to run smooth

 

k-jet injectors are totally different and don't have any electrical connection, they spray constantly as long as there is fuel pressure. the fuel lines to the injectors come from a 'fuel distributor', which has a venturi plate that measures airflow and meters the gas mechanically/hydraulically.

this is a 6 cyl k-jet fuel distributor from a mercedes 1990 300e (they used this old stuff 10 years longer than volvo)


anyways... that different LH injector may very well have a different flow rate, which would likely throw the LH computer off some. in theory it can tune for the differennce with the O2 sensor if its not TOO far off.

 

right iv seen that on some old mercedes mine is the LH for sure
just put on a new cap and rotor and replaced my engine mount same misfire at 3500rpm but it does seem to be running a bit better

 

whats the nature of this misfire? is it just like a little stumble, erratic loss of power, or is it more like a violent surge or backfire, or what?

one of my turbos had something like that where I'd loose power up around 4000 rpm wide open, turned out to be the hose between the MAF and the turbo was soft and getting sucked in so air was bypassing the MAF, so it was miscomputing how much fuel to use. replaced that hose, and whoa nelly, it wound up to the redline lickity, that 740T wagon can move when you stand on it.

 

oh. another thing to try. at night, in a dark place. pop the hood, rev the engine and look for any lightning display. that's a sign of bad spark plug wires. I've had almost new sets of aftermarket wires light up like fireworks. I got some proper Beru wires (this was on that benz 300E) and poof, no more ignition problems.

also check the wiring around the power module and the coil... if thats sketchy, it might not be delivering enough pookah for clean ignition at higher RPMs.

 

its a hesitation my volvo is N/A so any power i have i want to keep!! it takes a lot to get to speed. i just replaced my wires, plugs, cap, rotor, injectors, fuel, filter in the past few months. i dont expect it to be fast but just to run smooth
the idle is "ok" not smooth but steady
could it possible be worn cam lobes? or something else in the valve train? it has just over 95k miles from what iv seen thats break in for a red block!

 

i've never heard of any problems on redblocks with worn cam lobes, i'd have to imagine it would take some major engine abuse (like, running it with way too little oil for a long time, or with serious water contamination in the oil or something).

my daughter's 1987 240 has 400K+ miles on the original engine, still runs fine, burns no oil, passes California smog easily.

when its missing, its either not getting enough fuel, or its not getting a good spark. I'm not sure how to best determine which if its mostly happening at speed. if you pull the spark plugs, what do they look like? if they look black/sooty, its running too rich. if they look too white, its running too lean.

 

what is the injector psi on b23? b230?

 

LH2.x is 42-44 PSI relative to manifold vacuum at the injector rail

K-Jet was like 65PSI or something.

afaik, all B230 engines are LH (except for the regina ones, which use the same pressure). B23's are likely to be K-Jet.