Hello everyone, love my 940 Volvo 2.3 non-turbo , 234k miles and still kicking but I'm out of ideas with this one

- MAJOR loss of power, when driving in any gear it won't rev past 3k or 2500rpms, just hits a wall and has a hard time making it up the hill

- it's not a slipping transmission, then it would rev past 3/4/5k but car would just "not go" and slip , it's not doing that

- MAJOR idle surging , 200-1000rpms or so, even stalled once (which it never did before).

- in neutral/park it revs to 5500rpms just fine, so I'm thinking that rules out fuel pressure, spark problems (coil/distributor/rotor/plugs...)

- I have a service light and check engine light, when I try to pull the code from the A block with wire in port 6 I get 1-1-1 , which I guess means no codes?? confuse by this, but check engine sure is on now

- I pulled one plug, white-ish, not rich at all, no crud or damage

- nothing is leaking, everything "works" it's as if it's in some sort of limp mode


I've been hunting for a vacuum leak, but can't see one, plus once again wouldn't that affect revving in neutral/park too?

Do TPS/MAF/IAC all come into effect when in neutral/park? I was thinking it can't be TPS since that def works in neutral/park , MAF maybe but again shouldn't that affect revving all the time? and IAC I would imagine has nothing to do with driving


Thank you in advance for any ideas you may have.

 

is there a limp mode on these cars? and does it NOT apply when in park/neutral? that might explain some of my issues here where nothing is adding up.

 

another update, I just cleaned TB and IAC, they were both filthy , I also found one IAC hose with a crack and I replaced it, but... no difference.

It ran for maybe 1 minute then right back to the asme surging/no power. I did some more neutral/park revs to 5500 and IDK if it's revving slowly there too, it definitely gets to redline if I wanted it to but it's no spring chicken either while revving.

 

also, check engine is ON , but service light is off now, does it make sense that I can't pull any codes??? it still flashes 1-1-1 when I put the key to on and try to check for codes.

 

Could be a clogged catalytic converter. Can test by fitting a vacuum gauge to a port after the throttle body and hold the rpm's to 2500. If the gauge steadily drops, likely the converter is bad.

Usually, there is a sulfur smell to the exhaust. You can take a rubber mallet and gently strike the converter and listen for rattles.

I believe you can remove the O2 sensor upstream of the cat and then drive and see if the rpm's are more available

 

I'd look at the Power Stage block, on the inside of the driver's side fender toward the front--known to cause what you describe.

 

thanks guys, please keep the suggestions coming.

Problem now gotten worse, it's as if 2 minutes after car runs/idles (idles well first 2 minutes) it starts surging and today it was barely getting to 1500 rpms, 0 power or so, would even backfire, I think through exhaust but not sure... and with each backfire it would jump, so I ordered everything to redo ignition plugs/wires/coil/rotor/cap... I'm hoping that helps, but I doubt it

does anyone make an adapter to add Schrader valve so I can check fuel pressure???

 

740 Fuel Pressure testing - Turbobricks Forums

Not the cat?

What year is your 940?

 

pro fuel pressure gauge kits have a t adapter, you unscrew the fuel hose from the injector rail, and attach this tee in line, and it has a fitting for the pressure regulator.

the pressure regulator is relative to manifold vacuum. later cars are 42-44psi above manifold, older LH 2.2 240s were 36-38 PSI. really old k-jet cars are something completely different (in the 60s). so, at idle, your manifold is like -9 psi or something... so instead of 42-44, you'd see 33-35 psi with the vacuum hose connected to the regulator. open the throttle with the engine running and the pressure should go up. disconnect the vacuum hose to the regulator and it should be 42-44.

 

maybe this will help someone down the road, it's the in-tank assist fuel pump, I pulled #11 fuse and sure enough it ran just fine. It had nothing to do with the ignition parts I ordered, although they were all in awful shape so no real harm done , I will replace the pump tomorrow and hopefully be all set.

from what I read it may also be some cracked hose or whatnot, either way the pump is $50 so no big deal whether it's $50 or $3 , sure beats a new car payment.

 

I've had this same issue going on for a month now... mine will run amazing until 5k rpm. I replaced all the ignition components, all fuel components. All I can think of is the ignition control module or ecm. Mine will idle fine, run like hell, then hit 5k and it backs off almost like it hit a Rev limiter without the tapping tone.. just pauses then I let off the gas and back on it'll run until 5k... fine in neutral and park. Only in gear it does this. I have so far replaced ignition coil, plugs wires, cap&rotor, fuel rail, adjustable pressure regulator, all new vacuum lines, all new turbo piping and intercooler (no leaks), new gaskets everywhere and still the same issue. I have 111 across the board as well...

 

I pulled the #11 fuse and it worked! Car ran fine! Funny thing, the previous owner changed the pump. Maybe he messed things up. This is my second 940t and I picked it up for next to nothing. Have had to change just about everything under the hood this guy so called fixed lol. All is in working order now. Time for some upgrades haha

 

if removing the in-tank pump fuse improved things, I bet the pump is wired backwards such that its sucking rather than pushing fuel...

a lot of the aftermarket pumps are coming this way, wrong wire colors. I do believe I would take a new one, and a bowl of some kerosene or stoddards or something (much less flammable than gasoline), 'hotwire' the pump with a 12V battery and clipleads, and stick the intake end in the bowl and verify its pumping the right way. if its blowing bubbles, reverse the wiring.

 

That actually makes a lot of sense. Seeing that I replaced my fuel pressure regulator because my system wasn't holding proper fuel pressure when turned off. Still the same symptoms. But when I pulled the fuse and put it back in, the car ran fine... I'll check the pump this weekend to see what's going on. I ordered a higher out put pump anyways lol

 

the bosch turbo pumps already are high flow. the in tank pump is a 'delivery' pump, high volume, but low pressure, while the main pump makes the fuel pressure. it can deliver enough fuel to get worse than 10MPG if you're wailing on it, that will feed a pretty big motor.

 

I'm not certain, but the Volvo has a lift pump as a secondary? And the in tank to supply proper psi? Please correct me if I'm wrong. After purchasing my diesel truck, I kinda forgot how some of the b230ft are set up. Lol. Thanks for the info!!!

 

the in tank pump is a feed pump, the main pump under the car develops the fuel pressure. the feed pump is primarily there to prevent vapor lock, but it also helps the main pump out when the gas tank is below 1/3rd tank.