´96 850 engine struggles

[abscate]

Teddy, take a break and come back with a fresh set hands in a few days

Nice job on the manifold!

[Teddy1975]

Thanks

I couldn't keep away from the car today. I managed to cut the old rusted fuel filter out from under the car and put in place a sparkly new filter without setting the car on fire. I sort of wish that had happened, but unfortunately no.

Other than that, I'm resting my back hoping to get back in under the hood tomorrow to continue troubleshooting. I only feel like I'm spending a lot of time doing things I really don't have a clue about and getting my hands dirty for nothing.

Oh, I do find a lot of things that need to be taken care of, but they can wait until I figure out what is wrong with the engine. The way it's running makes me believe it's a bigger problem than just a bad sensor of sorts, but with absolutely no error codes set, it's like trying to find a needle in a haystack. Last time I turned the engine on it wouldn't rev past 2k rpm before it started stuttering and with throttle wide open it stalled to 300 rpm nearly dying. Still, the TPS is within spec, I think the code I pulled for it yesterday was only because I removed the connector with the engine on.

So I'm going nowhere fast.

/Teddy

[FLXC90]

Check your ignition coil/coil wires. Ignition breakdown under heavy loading. Either that or fuel is being restricted. You say it runs fine if not under load will rev as supposed to, but not under load.

[Teddy1975]

Hi FLX.

Thank you for your ideas. I've replaced the wiring about a month ago to Bougicord (Not sure if spelled correctly) but I didn't check the ignition coil. I did the wiring before all of this happened and it ran fine up until it quite quickly went downhill.

It idles fine at 850ish rpm and will do so happily until it runs out of fuel, if allowed to. As soon as I touch the throttle, it sputters and only gets worse the more throttle I give it. I can make a short recording of it, might be easier to see and hear what it does than me trying to explain it.

[scot850]

Sorry to hear of the issues you are having. Have you tried the throttle position sensor? I had a similar issue with my parents 850 NA and the TPS was the issue. The rider on that is it was ok at tick over, but bad when rev'd.

FLX90 has an excellent point on the coil, or a bad ground somewhere is another possibility. Had that issue with a 240 and it was a bad short in the distributor. Have you checked the distributor is dry and no oil leaking from rear cam seal? Checked the distributor cap and rotor arm for cracks?

Neil.

[Teddy1975]

Hi Neil, and thanks.

Heh, uh, it isn't as if I'm constantly monitoring the forums for replies, it's just I have it set to notify me when someone replies and I've been sitting in front of the pc.

When I replaced the spark plug wires, I replaced the distributor cap and rotor as well. There wasn't any oil back then, but I'll crack it open tomorrow and have a good look around.

I measured from just about 0.37 volts up to 4.2 volts on the TPS yesterday, from idle to WOT. As far as I could tell on my digital voltmeter, it was a smooth transition up the range. I tested it with ignition on, engine off, measuring volts on the two outer wires of the plug as per a youtube instruction.

Bad grounds is something I definately have to look into, the two smaller ground flex wires on the top of the engine towards the firewall are not in very good shape. I also have an indication of something not being fully right as the generator warning light flickers when I power off the engine. I haven't looked into that yet since I've never really seemed to have the time for it and it hasn't been a real pain in the rear until now. The generator itself is only one year old.

I'll go out early tomorrow and try to fix as much as I can and then make a post with my findings.

/Teddy

[Teddy1975]

Today I cleansed the grounds connectors I could find in the engine bay without removing too many things. Though the two flex wires looked extremely worn, they only had 0.4 ohms resistance after clean up and was reinstalled. I had a closer inspection of the spark plug wiring and the distributor/cap/rotor. No irregularities found, though I rearranged the wire for plug #3 to make it sit nicer with the rest of them in at the distributor. There was an old build up of oil behind the distributor, but must have been from before I sorted the PCV as it was all dried up and not much at all.

Turned my attention to the throttlebody and didn't like the look of it. It had an 1mm thick, black and burnt layer of oil all over. Took it off and found more of the nasty build-up in the intake manifold. I figured it wouldn't make much sense only cleaning the TB if the manifold was full of the same crud, so took the manifold off and hit it with first brake cleaner, then pure petroleum, and scrubbed it as well as I could with a bottle cleaner. It's not exactly mint condition now, and I'm sure there are areas inside the manifold I couldn't reach, but it is a lot better than when I started out.

Since I had the manifold off the engine anyway, I also had a look at the PCV. I fixed it about a year ago, replaced the OEM narrow line from oil catch to flame trap to 5/8" hose. I was quite happy to see none of the ports in the engine had been blocked, nothing but a bit of liquid oil there.

At this time it started raining, but I pressed on, put things back together and started the engine after priming the fuel rail a couple of times. It fired up straight away though it sounded quite strange when I gave it a little throttle. That's when I suddenly realized I had forgotten to reconnect the EGR brass pipe to the intake manifold. By that time the rain had gotten worse and I had to put away my tools.

To be continued, hopefully by tomorrow.

Sorry, no pictures or video this time, my hands got quite grimy since I forgot all about the latex gloves I've bought for this exact reason

/Teddy

[Teddy1975]

I got it all put back together properly and the check engine light came on right away when I powered it up.

I read out two codes:
2-4-3 and 1-2-2.
TPS and Air Temperature sensor.

I've ordered a new Bosch TPS and will have a look at the EGR temp sensor once it stops raining (again) and my work clothes are dry again.

Thank you for your support

/Teddy

Edit: I wrote some rubbish that didn't make any sense earlier.

[rspi]

Is the Cat clogged? Disconnect the exhaust at the back of the exhaust manifold and take her for a spin.

[rspi]

Also, double check timing.