I will start by saying that although I have checked a few different things, if you have any doubt about something, I'd be more than happy to check again.

Issue: Most of the time, when I step on the gas, it won't want to rev above a certain point. If I slowly let on the throttle, then I can slowly get more revs out of it, but if I just put the pedal to the floor, it won't want to rev very high and sputters. Most of the time I drive it, it does this, but every so often it runs perfectly fine, but that rarely lasts long before it does this again. It has gotten progressively more common. Here is what I have checked / replaced:

* Fuel
* Fuel pressure is at 3 bar during idle and 3.5 bar when throttle is opened.
* Fuel filter has been replaced (Old one was rusted and the fuel dripping out of the old one had a nice orange color to it)
* Fuel injectors have been replaced after replacing the fuel filter and seeing the rusty fuel coming out of it.
* Vacuum
* I have replaced a few different vacuum lines that were questionable, including the one that goes to the MAP sensor.
* Spark
* Spark plugs are reasonably new and gaps have been checked and adjusted. I did just learn that apparently using the circular gapper tools can damage the plugs if you use them to leverage against the center electrode (which I have done, so I will be replacing these asap)
* I put in a new set of spark plug wires
* New distributor cap + rotor
* Compression
* I have checked the compression on all cylinders and three of them read at 210 psi (14.48 bar) except for one that read at 220 psi (15.17 bar) after cranking twice for each reading. I repeated the test twice for each cylinder to make sure my readings were accurate
* Air
* I have cleaned the throttle body as well as thrown a new gasket on
* I have sprayed starting fluid around the intake hose and accordion and haven't found any leaks
* O2 sensor
* I did have an exhaust leak upstream of the o2 sensor, but after welding that shut, it still runs poorly and still gives a code 2-2-1 which says to 1. Check the o2 sensor, it could be faulty or 2. check the air intake. The o2 sensor is newer, and I have read the voltages from it while it's running in the video linked below.

* Other
* I have verified the TPS to be working properly.
* I have checked my valve clearances and found them to be out of spec. I am currently waiting on the valve compression tool, so I can change the shims.

* Exhaust
* I chopped off my cat and banged it out because it was rattling, and I thought it was clogged (it likely was). I then welded it on very poorly, but there isn't any leaks upstream of my o2 sensor, aside from a minor one on my down pipe near where it mates with the manifold. My 2nd muffler was rusted very badly and started sagging, and I was able to just pull it off with no tools, so I just have the one muffler.

Linked is an album of images and videos relevant to my troubleshooting.
https://immich.tomfoolery.online/share/0bmdWnIZ6Jhh1fEFm6m8o32w6vk_vX1v04AJuVHNTMLN0--TNokPhtf9-8e-FXTEkZ4

Hallo!

That's wild about the distributor being 180 degrees out and it still running. I did that to myself once and it wouldn't start, so I'm not sure how yours was running like that unless the firing order was reversed. Have you tried swapping the plug wires for cylinders 2 and 3?

When I've had issues with being unable to rev over a certain rpm, it was due to lack of ignition advance (rusted stationary mechanical spark advance on a motorcycle) or due to *very* poor mixture many times on my 740 turbo. Once it was a dead alternator causing the battery to not charge, but it only did that the last mile or so before the battery ran out.

What kind of line did you replace the MAP sensor line with? It should be *hard sided* polyurethane or tubing. You'll need soft rubber fittings on the ports to go from hard to soft lines.

What Oxygen sensor did you put in? Regina sensors are Titania-based, not Zirconia-based and they do not produce any voltage at all on their own. Instead of the voltage changing, the *resistance* changes and the sensor is fed a 1.0V signal that gives a varying output because the resistance between the input signal and ground is changing from 0 to quite high.
*If you put in a Zirconia sensor, your lean/rich readings will be _backwards_*.
Regina has 4 codes (per the FAQ) for O2 sensor being bad - one is for it being disconnected and the other 3 are for it not responding as expected. If you unhook the green signal wire and have an additional O2 sensor error code of 2-1-2, *or* if you have any voltage on that green wire from the sensor when the ECU is unhooked from it, then you likely have the wrong O2 sensor installed. Don't unhook the O2 sensor with the engine on or you could cause the power running through the sensor to find a new and unintended path to ground (short) inside the ECU.

If the fuel pump output line in the tank has leaks, the issues will disappear when the tank is full. If it's a crappy fuel pump, the issues will be random. I wonder what the fuel pressure is at 3k rpm?


I just tried to load your web link and got this error: "Error 1033 Ray ID: 8f87d5ee4af0a66c • 2024-12-27 08:10:42 UTC
Argo Tunnel error"

Good luck,
Will

Thank you for your info about the o2 sensor and the vacuum lines for the map sensor. I did not know about those specifics. I honestly couldn't tell you now what kind of sensor I had in, but I can say that I replaced some vacuum lines with silicone hose. I did end up putting the original vacuum line to the map sensor back, as I did notice things worsening.

I have since solved all rough / poor running issues by swapping in a custom ecu, posts about that are available here on BB. I have no doubt that there was more than just corrosion in the computer, but that was enough to make me go through with ditching the original electronics entirely and pave my own road. I wanted to do a custom ECU anyway.

As far as those argo tunnel errors go, my home server has been down for a bit now. I have a NAS that I built and host that Immich instance on, but I had only a single drive and it failed prematurely. I am having data recovery being done by the fine folks at Seagate and I hope to have the server back up soon. My understanding is that my data isn't destroyed, but I do have a backup elsewhere for this very purpose.
--
Nathan Micklatcher

I was not able to make any more headway on my own, so I bit the bullet and took it to a shop. I ended up at Housekamp's Auto Service in Grand Rapids, Mi off Division Ave South. They have been very reasonable on pricing, especially considering it has been there over a week now.

They found a few things:
* The timing was off by two teeth (thank god for non-interference engines), also I haven't touched this, meaning it's been running like this for more than a year :O
* There was a large vacuum leak around the 1st cylinder injector as I removed the plastic caps that came on the new injectors thinking they were protectors and nothing more. Turns out they hold the o-rings in place.
* The distributor cap was 180 degrees off (I didn't know it could even be put on wrong, unless they meant the way that the firing order was laid out.)

After diagnosing and fixing these issues (mostly caused by me) they found it ran a lot better, but the sputter above ~3000 rpm didn't go away. After making sure everything mechanical checked out, they looked at the computer and found some corrosion (not sure how much) in the connector. They tried cleaning it, waiting a day before reconnecting it, and still haven't had any success in eliminating the hesitation. On Monday (9/23), another guy they know that used to work on older Volvo's is going to look at it. If they aren't able to fix it, I'll probably end up having to put a standalone ECU on my car (which I wanted to do anyway, but was hoping to wait a while). If it comes to that, I will document the process on this forum.

Thank you all for your time and ideas on what to try. It means a lot to a novice home-mechanic like myself.

- Nathan

Hi,

I’m strictly a 240 man but we have closely the same running gear except for that Regina system. I have idea about them much except when they get a crappy connection somewhere it’s a challenge to find.
It sounds like the mechanics worked the car it over pretty good.
Between the timing belt being off two teeth but it having great compression might still be possible.
How distributor being off 180 degrees doesn’t seem to be correct.
As the wires on the distributor would still have to follow the firing order from where ever the number one cylinder was in the rotation.
Crossing over or off one cylinder by 90 degrees would have to be terribly rough if it would run?
Two teeth would be very noticeable in power loss.

As far as the hesitation on acceleration I want to point at the fuel pressure regulator in most cases especially if it anywhere near original.
The FPR dumps excess fuel back to the gas tank.
That orange gasoline and rust may be giving you issues from having a purring engine.

Is this a low mileage engine as the compressions have indicated?

The rubber diaphragm maybe stiffer than it should be and not as responsive to the “lack”of vacuum during acceleration. This increases pressure or volume out from the injectors. It job is about controlling the return valve to the tank.
Idling is higher vacuum and pulls the valve open to reduce volume that the engine might need to accelerate.

Are you have trouble with hard to start after sitting overnight or less?

The newer ECUs cover that up with their pre-running of the fuel pumps, prior to cranking.
It only a second or so long.
Listen for it for a first heads up to fuel pumps or loss of rest pressure problems. It supposed to keep the fuel rail filled.

I talked earlier about the AMM and air leaks so it look to me that around there was the biggest problem early on. Exhaust pipes and that itself, is all about air in and air out!

The BOSCH 016 AMMs have been very reliable but it’s not something that I would rule out as a possibility.
You said it sat a lot, so if it could be a wasps nest, go figure?
Make sure the electrical connections to it and the ignition spark relay “behind the battery” on the 240s are an overlooked item.

Good luck with a called-in mechanic it may help. It’s nice to respect those who admit their limitations and do that on your wallet. ????

Phil

My guess is the FPR is original. My fuel pump does run before cranking. The cars ODO reads 206,XXX miles, but the seller said that it was broken. In my experience, it seems to track miles just fine, but this engine is fresh by any means. The fuel rail holds pressure for over 5 minutes. No AMM, my car has a map sensor instead. Made sure that was working alright, engine dies when I pull the vacuum line going to it.

Currently the car has not run for about 3 months. I started the process of throwing in a custom ecu. I'm going to start a new thread about that and document my process. I believe I am approaching a first start soon, but the biggest issue during this all has been trying to get a crank signal.
--
Nathan Micklatcher

Hi there Michigan man.

Yep you have to have a CPS signal first or nothing works electronically with the fuel management system.

I responded to your post like 3 months ago and it was just after that the Brickboard site has been having fits in a sense of closing up shop! We as a group do not know why or if the web site is going to continue to survive.
I pulled my Sunday driver subscription after about six years and I think I have been on here since 2008.

I’m shocked that it sent me an email from your recent posting.

You say you don’t have a AMM but a MAP sensor but they are one and the same thing as both measure air volume. One is directly with air temperature as it passes where the other measures the lack of volume as a partial vacuum calculation through physics. Actually both are and have too be physics.

I went back and looked into the thread where you wrote about the car.
I now wonder if the car even ran before you got but the information about the speedometer mileage has me lost.
Having the timing and distributor issues was another one that a spin in gather information to begin a diagnosis.
I now wonder if the flywheel wasn’t off the engine at some time.
Possibly put back on wrong in relation to number one cylinder.
After that person realizes what they had done they turned to lopping the distributor around in 180 or 90 degree backwards to make up for it?
Otherwise it wouldn’t have ever run.

I don’t think you should play around with any make-shift ECU until you get the basics out of the way, so then, it will run decently.
Your phrasing about the engine. “engine is fresh by any means” has me thinking it was rebuilt or is of low mileage. Was it the reason for you getting it?

Is this your first Volvo?

“I believe I am approaching a first start soon, but the biggest issue during this all has been trying to get a crank signal.” This is my closing line, that maybe should have been my opening line, but then I’m confused and it’s been awhile since I have been on here.

Phil

This is the first car I have ever outright owned. I had a Prius before this but I needed something with soul. Knowing what I know now amazes me that it ran before as well, even if it did only run poorly. The guy who sold it to me said he had done quite a few different maintenance items including the timing belt, amongst other things. I didn't know too much about cars when I bought this and definitely not anything about redblocks. I was eager to learn about cars and how to work on them, and I had heard that old Volvos were easy to work on and that they don't really die. I wish the car was in a bit better of a mechanical state when I had gotten it but for better or for worse, it wasn't and I had to figure it all out.

Since your reply to my post, I have successfully gotten it running and driving with a custom ecu and tons of help. (Post about that available on my profile here) It runs better than it ever has during my ownership (since early april 2024). I can finally focus on other things than getting it running and wondering why the hell it is sputtering out above 3 grand. I have learned a lot and a lot of the knowledge I gained during the process of putting a standalone ecu in would have been helpful before I did that trying to get it to run okay. Either way, I'm happy with the way that things turned out and my car runs like a top.
--
Nathan Micklatcher

I was not able to make any more headway on my own, so I bit the bullet and took it to a shop. I ended up at Housekamp's Auto Service in Grand Rapids, Mi off Division Ave South. They have been very reasonable on pricing, especially considering it has been there over a week now.

They found a few things:
* The timing was off by two teeth (thank god for non-interference engines), also I haven't touched this, meaning it's been running like this for more than a year :O
* There was a large vacuum leak around the 1st cylinder injector as I removed the plastic caps that came on the new injectors thinking they were protectors and nothing more. Turns out they hold the o-rings in place.
* The distributor cap was 180 degrees off (I didn't know it could even be put on wrong, unless they meant the way that the firing order was laid out.)

After diagnosing and fixing these issues (mostly caused by me) they found it ran a lot better, but the sputter above ~3000 rpm didn't go away. After making sure everything mechanical checked out, they looked at the computer and found some corrosion (not sure how much) in the connector. They tried cleaning it, waiting a day before reconnecting it, and still haven't had any success in eliminating the hesitation. On Monday (9/23), another guy they know that used to work on older Volvo's is going to look at it. If they aren't able to fix it, I'll probably end up having to put a standalone ECU on my car (which I wanted to do anyway, but was hoping to wait a while). If it comes to that, I will document the process on this forum.

Thank you all for your time and ideas on what to try. It means a lot to a novice home-mechanic like myself.

- Nathan

Hi,

If I didn’t know better and I usually don’t, 😊 I would say that the sputtering is from an erratic air supply information channel.
Or a possible SPLIT-leaking accordion hose. How old is it? Check its condition.

You having to manipulate the accelerator, in the way you describe, is a way to fight the fuel management system when it’s getting bad electrical signals tripping the “limp mode” program.
It makes me think you are jumping in and out of limp mode. You are saying it is more so lately than not?

The symptoms mimic a bad Air Mass Meter or at least the connecting pins on the AMM. Power to it or signals from it.
The AMMs on this man’s 240s are on the same power circuit as the injectors.
This power comes from the failure prone system relay that Spook talks about.
Anything is possible and the pump history is an interesting tidbit to keep in the background.

Sputtering and stalling out are two different things and there’s a fine line to either one is existing.
Half of one, is some times better than nothing. 🤔 I bet there a discussion in there somewhere. 😊

Check for discrepancies at the AMM and backwards from there.
It seems that you have covered most of everything thing else since it starts quickly.
But shortly from that point on the ECU has to leave its defaults and use good information it’s not getting.

Most of the time those error codes are a shotgun blast at a barn wall.
Yes, you hit it but finding all the buck shot is … left up to this … how good of a hunter are you?
Think about the sequences and check for tracks and trails.

Don’t you just love the puzzles in our lives?😳

Good luck!

Phil

Dear Nathan2715,

Hope you're well and stay so! Intermittent spluttering on acceleration suggests fuel insufficiency. You've checked most of the mechanical elements of the fuel supply system, e.g., fuel filter, fuel pressure regulator, etc.

But what about the electrical elements, e.g., the fuel pump relay (most likely white, rectangular, on the main fuse block, behind the front center ashtray) and the fuel injection relay (aka the radio interference suppression relay, in the engine bay, very dark brown, rectangular, against the inner fender wall, close to the battery?

How many miles on this car? Have these relays ever been replaced? Is the single, in-tank fuel pump the factory-original item?

What about the ignition coil (square, mounted on the front of driver-side strut tower)? The contacts between the coil and its base may be invisibly corroded, so a cleaning with an aerosol corrosion-remover (e.g., Deoxit) may be wise.

If the fuel pump and fuel injection relays are factory original - and they should have dates on them - they might usefully be replaced. After nearly 30 years of service, they don't owe you even a penny.

Hope these suggestions help.

Yours faithfully,

Spook

Something curious, there is no fuel pump relay where there should be... Not sure if something about my car doesn't need one, or if someones been fooling around in there. I'm gonna go take a closer look

You've replaced the obvious ignition side stuff other than the power stage, which is more often associated with a no-start or stall when it goes, so I wouldn't get too excited about that just yet other than cleaning up the connector. Closest ignition symptoms I've had to yours are a loose spark plug boot not making a good clamp contact on the spark plug cap -pushing it down would temporarily make a diff.

Bad hesitation during heavy acceleration, but being able to feather it up to higher revs and have it running half-normal really smells of fuel starvation to me. I'd add a new fuel filter to your maintenance item list. IMO your symptoms don't really match air starvation, but you should still check your air filter as a quick and easy thing to do.

If the problem continued I'd then want to check the fuel rail pressure (in a pinch, a tire gauge can be used on the Shrader valve to get a crude reading, you want to see in the order of 25-35 psi, not 10-20). I might even go so far as lifting the fuel rail and wanting to measure injector fuel flow into cups to make sure they're flowing evenly.

I wouldn't worry too much about the fuel pump or fuel pump relay. They tend to either work or not work, so are most often associated with a no-start. In the later B230Fs they changed the fuel pump relay from the tall white relay (middle row left) to a small cube relay (front row, second from right, typically blue, green or even black). The B230FTs kept the old white relay on the left. Hella is considered a decent aftermarket brand for the cube relays (Streibel for the white ones).

It's almost like you're running in limp home mode. I'd thought about adding a failing MAP sensor to your suspect list, but I don't think that matches your symptoms of being able to sustain a higher rpm. You've got a Check Engine code going anyway from the O2 sensor, so wouldn't know if limp home mode was happening unless you saw other codes.Just for jokes, disconnect your MAP sensor to force limp home mode and if the stumbling under acceleration doesn't get worse then you know that's it.

Similarly, a 2-2-1 O2 sensor code does not set limp home mode, but at some point you need to deal with that outstanding O2 sensor problem. O2 sensor issues generally affect fuel economy, not hesitation during acceleration, but it could be a contributing factor. If the Check Engine light comes on almost immediately after starting and letting it idle then I'd suspect the O2 sensor and its wiring, not an air leak. I assume there are no other codes on ports 2 or 6 (each side can store up to three different DTCs).

Much further down the suspect list would be the knock sensor. They only set a code when they outright fail or are accidentally disconnected. Is there any pinging during acceleration?
--
Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

Thank you for your reply.

The fuel pump has been replaced twice according to the previous owner, not sure what with. He said that when they went out, they just went out and there were no gradual issues.

As for the relays, they are original; I can order replacements. In the meantime, I'll give the ignition coil a look and clean.

After throwing new sparks in, it runs about the same. The car has about 205k miles on it, but the previous owner said that the odometer isn't working properly. Not sure on that, as it has tracked every mile I have put on it since owning it. It's possible that it wasn't working for a while, then was fixed and has a few untracked miles on it, again not sure.