98 V70 GLT Rough Start, miss RESOLVED bad fuel inj

[taupehat]

151k miles, currently my daily driver. I'm really puzzled by this.

• Issues as I'm seeing them:
• Rough start: Cranks for about 10 seconds, starts very reluctantly. Runs rough for about 30 seconds, white smoke and running super stinky rich. Then it's fine. Starts perfectly if shut down for 5 minutes or less.
• Intermittent miss on 5: Enough to activate the CEL about once a week or so, always when it's been shut down for half an hour to an hour. Never when started cold. Plug in 5 smells of gasoline and is wet. Miss never shows up on any other cylinder.
• "Weird" power profile: Acceleration is steady on a half-pedal or less. When I push it to the "stop" (not the floor, the part where the pedal gets harder to press) I get about one second of strong accel followed by a really binary transition to superpower blast-off head-snapping turbo goodness. I know this sounds like turbo lag, but I've owned turbocharged cars before and the transition was always a bit smoother. This feels a lot more like I'm going from 4 active cylinders to 5. With the windows down, I hear a hiss before the boost kicks in and that sound goes away once I get the boost.

• What I've done thus far:
• New plugs, wires, cap and rotor. Pretty sure two of the wires were factory originals. Brittle, ugly, wore out, bad terminals, etc. Weirdly, three of the wires were somewhat newer and a different brand. Cap and rotors were a shambles.
• Compression test: 165-180 across all cylinders. Cylinder 5 tested twice at 170.
• Tried unplugging the MAF to see if that helped with the rough start. No difference.
• Air filter. Yeah.
• 3x tanks with Tecron

So, the rough start and int miss on 5, do you think they're related? Part of me thinks maybe it's an injector, but I am not sure how to test the theory. It's hard to tell whether I'm conflating separate issues. Any further suggestions for trying to figure this out? Paging Dr. Volvo-House

[jreed]

Welcome to the forum!
Great post - good detail!

Do you have any codes and is the Check Engine Light on?
What type of ignition wires and plugs did you install?

For the boost delay, it could be a broken or leaking vacuum line to the boost control solenoid. What condition are the vacuum lines in?

[abscate]

I think its time to play "the 64000 USD swap game"

Move FIJ # 5 to cylinder number 2 and see if the problem moves with the injector.

One last less drastic thing is to listen to the injectors with a rubber hose, the colour of which must match the original exterior paint of your car, and see if FIJ 5 'sounds different (Mrs Gump) than the others...dont let your neighors see you doing this or they will call the authorities....

[taupehat]

Welcome to the forum!
Great post - good detail!

Do you have any codes and is the Check Engine Light on?
What type of ignition wires and plugs did you install?

For the boost delay, it could be a broken or leaking vacuum line to the boost control solenoid. What condition are the vacuum lines in?

Thanks! Anyhow, I get P0305 or sometimes prefailure P0305 (the Torque app is pretty awesome IMHO).

Plugs are Autolite copper, wires are Import Direct. I'm loathe to say "that's not the problem" except that I had exactly the same code before I replaced all that.

Won't have time to give the vacuum lines a good going over until later on today, but will definitely do that and let you know what I find.

[taupehat]

I think its time to play "the 64000 USD swap game"

Move FIJ # 5 to cylinder number 2 and see if the problem moves with the injector.

One last less drastic thing is to listen to the injectors with a rubber hose, the colour of which must match the original exterior paint of your car, and see if FIJ 5 'sounds different (Mrs Gump) than the others...dont let your neighors see you doing this or they will call the authorities....

I'm trying to imagine the reaction my neighbors would have at me using a teal green garden hose to listen to the engine of my car. Then again I'm trying to imagine me not getting the damn hose caught in the serpentine belt while I listen to it. Swapping the injectors and seeing if the problem follows the injector is a good idea though.

[E Showell]

These cars are very sensitive to OEM-only ignition components. Bougicord only for the plug wires.

[socompsp]

are you sure of the colour of the smoke? what does it smell like? turn your heater on and smelligate. from your compression results i have doubts about head gasket issues, but if its white smoke at first start you could have a very slow leak seeing as your coolant system holds pressure after the car is turned off. (this is when leaking would occur?) for sure check your injectors, although id be rather careful removing hem if they are aged, check the electronics going up to them as well, spotty connections leads to spotty fuel delivery. was the compression test done cold before first start or warm. id try it when youd expect to have the starting issue, could have a loss of compression until oil circulates and seals rings? plug 5 is wet, with what? i know it smells of gas but your injectors firing will cause that anyhow. like i said i doubt you have coolant leaking into that cylinder, so im gonna guess and ignition issue. when you go to start it in the morning or when youd expect to have the issue, peek inside said cylinder and see if you find anything odd. the only code you are getting is a misfire code? you say it smells super rich id think that would set off an o2 code or posibly an injector code. when the cel comes on does it blink after say 2500-3000 rpm? perhaps try another scanner? i know my innova gave me a p0306, and i have a 5cyl..

[taupehat]

Comp test was done warm-ish, which is when I most often get the CEL activated. It's really at its worst when shut down for an hour or so. Overnight, it starts rough but quickly sorts itself out. Semi-warm is when I get a very clear miss - engine runs rough and I can hear the cylinder not firing. Again, that sorts out pretty quickly but by then the CEL is lit up.

CEL never, ever flashes. I've had codes pulled by 3 different devices, and always the same P0305 code. I say it runs rich only by the evidence of my nose - strong gasoline odor when the engine is running poorly.

Pretty sure checking the injectors is going to be my next step as it seems like the most likely cause for the #5 problem. It's just not something I look forward to having to do: the crunching sound of a breaking injector fills me with dread.

Thing is, can anyone think of a unified theory for why the persistent issue on #5 would relate to the rough start?

[socompsp]

well if that injector is flooding cyl 5 thats gonna be your problem. but once agian that causes a cel, usually. and its a specific code, not just a mis code. also check the gap on your plug.

[taupehat]

Yeah, I get the CEL, no flash but solid CEL. Replaced the plugs, wires, cap, and rotor, that was good for a slight overall improvement but not a fix to the problem.