• Hello Guest, welcome to the initial stages of our new platform!
    You can find some additional information about where we are in the process of migrating the board and setting up our new software here

    Thank you for being a part of our community!

Regina gremlin is driving me crazy

T

TheAllOriginal89

New member
Joined
Jun 1, 2013
Location
Jersey
Here's the story, been a volvo owner for decades, had many 240s and now 2 740s. My current vehicle is a 1991 740 base sedan automatic. Regina ignition system is new to me and I think the root of my problem. Initially the car was poorly maintained so I went to work. In the time of ownership I have replaced the following:
MAF sensor, ignition coil, ignition control module, IAC, crank position sensor, plugs, wires, battery, O2 sensor, throttle body gasket, intake manifold gasket, fuel pressure regulator and the intake system is clean. Although the car now runs better the RPMs dive to 500 and under in drive or reverse. The car is regularly in danger of just quitting in the middle of traffic and with accessories on it is worse. I installed a volt gauge to monitor while I drive and it charges appropriately but at 500 rpms and under it barely charges enough to do anything. I swapped the bulbs to LED to decrease the demand but I'm at a loss. It's been a lot of money in parts and time and I love this car but it's useless if it isn't reliably running. As an FYI, I had a shop fix the A/C system, there has been no change in running condition other than dogging the motor down further. Compression is good and just driving at speed seems OK but stop lights and slow driving kill it. I have to shift to neutral to keep the engine alive at a stop in traffic. Any ideas? If I can't solve this I'll have to get rid of it
 
TheAllOriginal89 said:
replaced the following:
MAF sensor, ignition coil, ignition control module
Click to expand...

Are you sure it's Regina? Regina uses a small MAP sensor instead of a MAF, and a weird Rex coil assembly with the ignition module integrated into the coil assembly.

Is the IAC working? When you start it cold, does it idle at a faster speed until warmed up? Is the TPS idle switch adjusted correctly?

Fuel Injection

Repairs and maintenance of the fuel injection system
www.volvoclub.org.uk
 
If you want to try an icu or ecu I have both out of a 94 940,
there is a also little vacumn sensor on the drivers side under a strut going to the firewall, can’t remember what it does but it’s engine control related.
 
Last edited:
TheAllOriginal89 said:
Although the car now runs better the RPMs dive to 500 and under in drive or reverse.
Click to expand...
As stated, the Throttle Position Sensor needs to be adjusted so it clicks just as you crack the throttle open. With the throttle closed, the internal contacts close and tell the ECU to go into "idle" mode, which opens the IAC a pre-programmed amount.

Does it idle properly if you pull the IAC hose off the airbox?
Can you feel any suction with it off?
Can you kill the engine by squeezing the hose and cutting off any air?

My poor ol '90 also had a "low idle" problem for years.
I just got used to it, until I got ambitious one day and did some in-depth investigations.
Turns out my air filter box had been changed to one from the wrong type of 740, LH instead of Regina.
The idle air hose was connected to a blocked-off port (LH gets air from the intake hose, not the box).
I drilled out the not-a-hole, and it then idled perfectly.
Maybe yours has a similar problem?


blocked-airbox-1.jpg

blocked-airbox-2.jpg
 
Dealt with this exact problem myself on my own 1991 740. It ended up being the fuel ecu. One notable symptom was that if I disconnected the battery and reconnected it, I would get the normal high idle IAC function on the first start, but no other starts until I disconnected the battery again. Start with the IAC valve, you can check in DTM 3, the same test mode that pings the injectors, if it can get a signal from the car. You should be able to hear it and feel it clicking if you put your hand on it. If that works, pull it and clean it out with brake cleaner if its dirty and apply 12v to it to open it. (There is a tiny + and - printed on the pins) It should be completely closed without power as well, no flow, and fully open with lots of flow with 12v applied. You can also soak it in some gas for a bit to really get all the grime out. If everything checks out here, your IAC is good. A quick check for airflow from your airbox to the manifold in the iac hoses is also worth verifying but I doubt yours are blocked. Replacement IACs for regina are NLA and expensive online, so don't fire the parts cannon. Next is to check the TPS. It should click just off idle and at full throttle (no need to have the engine on). If not it needs to be adjusted with feelers, but check first. Check for continuity changes between idle, off idle, and full throttle settings as well. if your TPS is working right, IAC is working right, and the car can ping the iac in DTM3 and has a signal to it, the next culprit is the fuel ecu on the right hand side kick panel. I was going crazy trying to get my idle right, same problems you have. Shotgunned a green label 1992 regina fuel ecu at it after everything else seemed fine and it works again. You probably have an orange label ecu in there right now. Mine looked perfect inside but must have had some kind of failure in the idle circuitry somewhere. I suspect it's a bad design in the earlier regina cars that was fixed in the later ecus (someone said 93+ are better? not sure how true but the later ones are hard to find online) The ignition and fuel ecus are cross compatible over different years without issue either. I'm almost certain this should fix your issue if you follow these steps.
 
NLRegina said:
Dealt with this exact problem myself on my own 1991 740. It ended up being the fuel ecu. One notable symptom was that if I disconnected the battery and reconnected it, I would get the normal high idle IAC function on the first start, but no other starts until I disconnected the battery again. Start with the IAC valve, you can check in DTM 3, the same test mode that pings the injectors, if it can get a signal from the car. You should be able to hear it and feel it clicking if you put your hand on it. If that works, pull it and clean it out with brake cleaner if its dirty and apply 12v to it to open it. (There is a tiny + and - printed on the pins) It should be completely closed without power as well, no flow, and fully open with lots of flow with 12v applied. You can also soak it in some gas for a bit to really get all the grime out. If everything checks out here, your IAC is good. A quick check for airflow from your airbox to the manifold in the iac hoses is also worth verifying but I doubt yours are blocked. Replacement IACs for regina are NLA and expensive online, so don't fire the parts cannon. Next is to check the TPS. It should click just off idle and at full throttle (no need to have the engine on). If not it needs to be adjusted with feelers, but check first. Check for continuity changes between idle, off idle, and full throttle settings as well. if your TPS is working right, IAC is working right, and the car can ping the iac in DTM3 and has a signal to it, the next culprit is the fuel ecu on the right hand side kick panel. I was going crazy trying to get my idle right, same problems you have. Shotgunned a green label 1992 regina fuel ecu at it after everything else seemed fine and it works again. You probably have an orange label ecu in there right now. Mine looked perfect inside but must have had some kind of failure in the idle circuitry somewhere. I suspect it's a bad design in the earlier regina cars that was fixed in the later ecus (someone said 93+ are better? not sure how true but the later ones are hard to find online) The ignition and fuel ecus are cross compatible over different years without issue either. I'm almost certain this should fix your issue if you follow these steps.
Click to expand...
Thanks dor the quick reply. The airbox isn't obstructed or anything. The TPS was not replaced and I adjusted it to the best of my ability but I also do not have any real experience with them. I had to pull it off the really clean the butterfly and check for any other issues. The kick panel module looks ok but then again that means nothing. I took it apart and checked actual wire connections and it seems to be fine. Oddly after doing that and having the battery disconnected, it did what yours did. Seemed ok until it wasn't. But now it starts and idles at 150 maybe. Weirdest thing. It doesn't die either. It just sits at that. The module replacement is my next step. They aren't too bad second hand and I'm thinking you are right about that. The OBD tests revealed everything is working. The IAC is new, I bought it from some special vendor and it's an original VDO. Set me back 550 bucks and I was hoping that was the problem. I'll look into new computers for it
 
bobxyz said:
Are you sure it's Regina? Regina uses a small MAP sensor instead of a MAF, and a weird Rex coil assembly with the ignition module integrated into the coil assembly.

Is the IAC working? When you start it cold, does it idle at a faster speed until warmed up? Is the TPS idle switch adjusted correctly?

Fuel Injection

Repairs and maintenance of the fuel injection system
www.volvoclub.org.uk
Click to expand...
Def regina. I mistyped but it has the little map sensor in the intake hose (replaced with new unit) and the IAC is brand new. In park at start it's fine and idles fairly well. It's just in drive or reverse it drops precipitously and is almost dangerously low bouncing between 450 and 500
 
TheAllOriginal89 said:
Thanks dor the quick reply. The airbox isn't obstructed or anything. The TPS was not replaced and I adjusted it to the best of my ability but I also do not have any real experience with them. I had to pull it off the really clean the butterfly and check for any other issues. The kick panel module looks ok but then again that means nothing. I took it apart and checked actual wire connections and it seems to be fine. Oddly after doing that and having the battery disconnected, it did what yours did. Seemed ok until it wasn't. But now it starts and idles at 150 maybe. Weirdest thing. It doesn't die either. It just sits at that. The module replacement is my next step. They aren't too bad second hand and I'm thinking you are right about that. The OBD tests revealed everything is working. The IAC is new, I bought it from some special vendor and it's an original VDO. Set me back 550 bucks and I was hoping that was the problem. I'll look into new computers for it
Click to expand...
The TPS is just an analog switch, it's nothing fancy - as long as the metal strips inside can contact at different positions it should work fine. If you can hear it click on the first movement of the throttle spool its almost certainly working right, and if not its pretty easy to just loosen the screws and adjust it slightly and retighten. Doesnt need to be perfect, just enough that it can tell the ecu when your foot is and isnt on the gas. If you really want to be certain its good, check for continuity changes at the plug depending on the modes. There might also just be a diagnostic test for it with the OBD module, cant remember. Let us know how it responds with the new ecu though, I bet that'll solve it.

Also, I had the same low idle reading issue on mine too, reading around 100-200 sometimes, and then perking back up to realistic readings under throttle. These engines can realistically idle as low as 400-450 rpm, so if the tach is reading lower it's wrong. I read here that a degrading coil/coil module can cause a bad reading, since thats where the idle speed reasing comes from. I had already replaced the coil, but the coil module where the coil bolts in was the likely culprit. It's expensive under the volvo name but it's a jeep part too, and summit racing has them new for sale. (Theres some cheaper ones out there on amazon but Ive heard bad reviews about some of them, although I think O reillys might have one for cheaper than summit) I replaced that bit and haven't had a tachometer issue since. make sure the connections to that module are good as well, no corrosion etc.

Finally, I had some bad shuddering in reverse in mine as well. I think it was partially my idle issues and partially because I had the transmission oil too low after a filter replacement and flush. You're supposed to check the level when the car is running, not when it's off - it's lower during operation. Mine feels much better after I got it to the correct level.

Also another bit of advice: Don't use Pro Parts Sweden motor mounts. During my idle issue/vibration saga, I thought my original hydraulic mounts were bad because of all the shaking, but the pps mounts I replaced them with were so much stiffer than OEM and made things much worse. I never should have thrown out my originals. There are no more oe/oem suppliers, so you'll have to find used or NOS replacements if you need good engine mounts.
 
landlockedsurfer2 said:
If you want to try an icu or ecu I have both out of a 94 940,
there is a also little vacumn sensor on the drivers side under a strut going to the firewall, can’t remember what it does but it’s engine control related.
Click to expand...
The ecu i am interested in. The icu i swapped with a new unit. No improvements. That vacuum line probably goes to the cruise control. I disabled mine when I cleaned the intake because i wasn't interested in using it and it wasn't working anyway
 
That's the MAP sensor, it's a GM part and pretty readily available and cheap too. Worth replacing as part of a full system tune up if you really felt like it, but I think it would be throwing a 1-2-1 code if it was bad.
 
bobxyz said:
That's a deal, if I had a Regina system, I'd buy it just as a spare.

A partial copy of the Volvo Regina Greenbook can still be found here:

Not sure if it will help. Have you tried pinching off the IAC hose to see if it's actually doing anything?
Click to expand...
I had popped it off and it seemed to breathe easier but the way it idles it never seems quite right. It hunts at idle between 550 and 750 in park sometimes and other sits dead at 750 and is fine but as it warms up drops to 550 or 600 and isn't smooth. That's what makes this frustrating because the engine doesn't run badly, it just doesn't run the way it needs to regularly in reverse or drive to make it useful. I am going to pull the accessory belts off and recheck the pulleys. I heard a squeal and the power steering pump looks worse for wear so I'm really hoping that the bearing is garbage and that resistance on the crank would dog the engine enough to cause issues.
 
landlockedsurfer2 said:
I can sell you the ecu and that mystery thing..... $75 shipped for both? long as your in the 48
Click to expand...
In NY I'm not opposed to that deal. The mystery thing I'm interested in. The ECU is probably an exercise in futility but it would be good to have something to compare the current unit to. Blown away by how problematic this system is compared to the Bosch systems.
 
Not perfect but slightly better..allow me to explain...the idle is now all over the place but is better in drive and reverse. The tachometer seems to be glitchy now as if it's signal is being interrupted and when in park the idle moves gradually from 900rpms and creeps to 1300. I lifted the pedal with my foot and that did bring it back down to something more normal. This all sounds discouraging BUT the issues now seem to jive more with other volvo issues I have read about. So maybe it's the TPS or the something in the linkage. Any further ideas?
As an aside I only started the car and let it warm up a little bit. My power steering belt popped so there wasn't cooling so I couldn't drive but just wanted to try it out.
 
You must log in or register to reply here.
Back
Top