Tandem Control Valve causing poor idle/driving performance?
Hondammit
Band Wagon
Car: 1990 Wagon, stock D15b2, auto trans
So last weekend, I replaced a broken exhaust valve in my wagon. Marked cam and belt at TDC and all that, put everything back together the way it came apart, and cranked the car up. It fired up immediately, idled a bit high, but I attributed that to having pulled the throttle and kickdown cables loose. I adjusted those, and the car seemed to run fine, for a minute at least. After running for a few minutes, the idle dropped and started surging. Looked around, didn't see anything apparent, but I had to get the car home since it was 2am, so I drove it home. At low RPM, it stuttered and missed a few times, but once it got up, it ran fine. Better than it had in a while, actually. Got home, let it sit overnight, drove to work, still had the same surging issue, but I expected that. The next day, I looked around under the hood, and noticed I'd missed plugging in what's labelled as the Tandem Control Solenoid Valve. So I plugged it back in, and my idle surge went away. I thought the problem was fixed, until I tried driving it. First, it idled at around 2000RPM when the engine was cold, then dropped dramatically, and it died as soon as I put it in gear. It also won't stay idling with it plugged in. It barely moves in low RPM, and I had to stand on the throttle just to get it to creep, until I got to a downhill grade and the RPMs ran up and the car drove like normal, until I had to come to a stop, then the same issue. Could that valve cause this problem? I can't really find any info on what this valve actually does. Before my exhaust valve bit the dust, my car ran flawlessly. Idled great, accelerated as well as a DPFI D15 could, got great fuel mileage. But now I'm just frustrated. I made sure my engine timing was lined up properly, I have no intake leaks that I can find, no vacuum leaks that I can find, the IACV has been cleaned, etc. Any help would be greatly appreciated.
*edit*
So after I posted this, I took it out for a drive to get specifics. Car idles low (around 500) in neutral, and I have to kick the throttle a little when putting it into gear to keep it running. Once it's moving, it stutters for a second, until RPM gets to around 1500, then it accelerates, but I can feel it hesitate until it gets to around 2500, in which time the car straightens up and runs right. Pretty much consistently each time I take off from a stop. Generally, I'd think it was a timing issue, which I haven't ruled out yet, but I'd like to get an answer on that valve first.
So last weekend, I replaced a broken exhaust valve in my wagon. Marked cam and belt at TDC and all that, put everything back together the way it came apart, and cranked the car up. It fired up immediately, idled a bit high, but I attributed that to having pulled the throttle and kickdown cables loose. I adjusted those, and the car seemed to run fine, for a minute at least. After running for a few minutes, the idle dropped and started surging. Looked around, didn't see anything apparent, but I had to get the car home since it was 2am, so I drove it home. At low RPM, it stuttered and missed a few times, but once it got up, it ran fine. Better than it had in a while, actually. Got home, let it sit overnight, drove to work, still had the same surging issue, but I expected that. The next day, I looked around under the hood, and noticed I'd missed plugging in what's labelled as the Tandem Control Solenoid Valve. So I plugged it back in, and my idle surge went away. I thought the problem was fixed, until I tried driving it. First, it idled at around 2000RPM when the engine was cold, then dropped dramatically, and it died as soon as I put it in gear. It also won't stay idling with it plugged in. It barely moves in low RPM, and I had to stand on the throttle just to get it to creep, until I got to a downhill grade and the RPMs ran up and the car drove like normal, until I had to come to a stop, then the same issue. Could that valve cause this problem? I can't really find any info on what this valve actually does. Before my exhaust valve bit the dust, my car ran flawlessly. Idled great, accelerated as well as a DPFI D15 could, got great fuel mileage. But now I'm just frustrated. I made sure my engine timing was lined up properly, I have no intake leaks that I can find, no vacuum leaks that I can find, the IACV has been cleaned, etc. Any help would be greatly appreciated.
*edit*
So after I posted this, I took it out for a drive to get specifics. Car idles low (around 500) in neutral, and I have to kick the throttle a little when putting it into gear to keep it running. Once it's moving, it stutters for a second, until RPM gets to around 1500, then it accelerates, but I can feel it hesitate until it gets to around 2500, in which time the car straightens up and runs right. Pretty much consistently each time I take off from a stop. Generally, I'd think it was a timing issue, which I haven't ruled out yet, but I'd like to get an answer on that valve first.
Comments
Regarding the IACV though I think there's only so much cleaning that can be done on them. There's parts that you can't get to to adjust like others.
I know you said you marked everything, but are you sure you got it back together right? There are two sets of marks for timing dependent on if you're running a 1.5 or 1.6
When I put mine back together the first time after the timing belt went on me I had it set for the wrong one and it caused very such performance but then ran like a champ once it got higher in the RPMs.
It sucked ass at Idle as well, I can't recall if it's exactly like you describe but that does sound familiar. So I'd double check that timing and make sure you're not a tooth off.