Not sure on air temps, i didn't ask. Boost is 8-10 psi
CK5
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Pigeon-Rat - Opel gambler build
- Thread starter ashman
- Start date
1966 Opel rekord mounted to 1990 Nissan pathfinder.
You're up at altitude there in SLC? Google says 4k ft?
Yup, 4200 as I recall.
That's gonna have some affect on the numbers. But hopefully they come up a little next go round.
Are you tuning for 91 Octane? You can up the timing or up the boost for more power - some engines prefer one over the other. For example, without an intercooler, sometimes the added heat from more boost starts to cancel out the effect of more pressure. The supercharger pulley looks pretty small, but maybe there is a larger crank pulley available. Sometimes the biggest gains with a roots blower is in the cam, but they are also sensitive to exhaust backpressure. In the end, you don't want "boost", as it's partly an indicator of restriction. You want airflow. In my Buick I had like 75% more torque than the stock configuration, but max boost was like 3psi more than stock because the intake and exhaust tracks were all opened up.
You can probably find all the tips and tricks on Nissan sites, but I would be more concerned with reliability and usability. The low torque curve looks pretty good for a wheeler and it makes you wonder if there's actually more torque below where they're measuring.
You can probably find all the tips and tricks on Nissan sites, but I would be more concerned with reliability and usability. The low torque curve looks pretty good for a wheeler and it makes you wonder if there's actually more torque below where they're measuring.
Yes, I will be running 91 octane. The gas in the tank at the time of tuning was old though, so another reason the tuner was cautious about adding too much timing.
As for air flow, I do have upgraded Jim Wolf cams and headers.
I do agree that reliability is the primary concern at this point. I've done about as much as I want afa increasing hp for now. Now I just want to be able to control and monitor the engine effectively.
I got the head gaskets replaced. The machine shop took a couple thousands off, but basically they weren't what you would consider warped. He said that any time you unbolt aluminum heads you can expect a couple of thousands worth of distortion.
I replaced the thermostat just because, but I tested the old one and new one in water over the stove, and both of them opened right up at 180*.
I'm not sure why it was overheating in that case. I guess with the blown head gasket, the water just wasn't circulating correctly? I've been driving it around with the laptop hooked up to the ECU to monitor temps, and so far it's stayed good. problem solved I guess. While I was at it, I got a knock sensor installed, and ran the wiring back to the ECU. Next wednesday I'll be taking it back to the tuner to double check everything and maybe give it a bit more timing. We'll see if the numbers improve.
For now, she rips pretty good.
I did run into a bit of an issue a few days ago. After one of my stops, I couldn't get it started again. The starter would barely crank the engine:
View attachment 20250113_164708.mp4
At first I was thinking dead battery (although it's new), or bad starter. It also was suggested that it was acting like the timing was way off, but given the recent tune that didn't make any sense (unless I messed it up putting the engine back together doing the head gasket).
I was able to verify that the battery was fully charged, so then I was thinking bad starter. I went home and got my trailer and when I went to load it up (about an hour later), it started right up, although a touch sluggishly. It had been starting that way since I got it back running, so that seemed to point to a bad starter, but I pulled it and it tested good.
So then I started looking for bad connections. I was at NAPA when it wouldn't start initially, so they put a jump box on it, and not only did that not help, but I guess it blew up the battery on their jump box.
That points to the starter pulling too many amps, so again, bad connection. All of my grounds looked good, and the power cable to the starter was tight, but then I noticed the stud on the starter was loose.
View attachment 20250114_182145.mp4
It seemed like wiggling that would have made the starter work intermittenly, not just poorly, but after tightening up the stud and reinstalling everything, she starts better, and quicker than ever. I'm calling that a win!
View attachment 20250113_164708.mp4
At first I was thinking dead battery (although it's new), or bad starter. It also was suggested that it was acting like the timing was way off, but given the recent tune that didn't make any sense (unless I messed it up putting the engine back together doing the head gasket).
I was able to verify that the battery was fully charged, so then I was thinking bad starter. I went home and got my trailer and when I went to load it up (about an hour later), it started right up, although a touch sluggishly. It had been starting that way since I got it back running, so that seemed to point to a bad starter, but I pulled it and it tested good.
So then I started looking for bad connections. I was at NAPA when it wouldn't start initially, so they put a jump box on it, and not only did that not help, but I guess it blew up the battery on their jump box.
That points to the starter pulling too many amps, so again, bad connection. All of my grounds looked good, and the power cable to the starter was tight, but then I noticed the stud on the starter was loose.View attachment 20250114_182145.mp4
It seemed like wiggling that would have made the starter work intermittenly, not just poorly, but after tightening up the stud and reinstalling everything, she starts better, and quicker than ever. I'm calling that a win!
Been there, it sucks until you stumble on it.I did run into a bit of an issue a few days ago. After one of my stops, I couldn't get it started again. The starter would barely crank the engine:
View attachment 495640
At first I was thinking dead battery (although it's new), or bad starter. It also was suggested that it was acting like the timing was way off, but given the recent tune that didn't make any sense (unless I messed it up putting the engine back together doing the head gasket).
I was able to verify that the battery was fully charged, so then I was thinking bad starter. I went home and got my trailer and when I went to load it up (about an hour later), it started right up, although a touch sluggishly. It had been starting that way since I got it back running, so that seemed to point to a bad starter, but I pulled it and it tested good.
So then I started looking for bad connections. I was at NAPA when it wouldn't start initially, so they put a jump box on it, and not only did that not help, but I guess it blew up the battery on their jump box.
View attachment 495639
It seemed like wiggling that would have made the starter work intermittenly, not just poorly, but after tightening up the stud and reinstalling everything, she starts better, and quicker than ever. I'm calling that a win!
After all of the above fixes, I took it back to the tuner.
New head gasket, fresh 91 octane gas, and a knock sensor. She's now making 184hp. It's an 18hp gain.
For some reason it's still idling around 1200rpm, so I gotta track that down (confirmed that the IAC is working). Working theory is some sort of vacuum leak, but I haven't found anything yet.
Other than that, it's just gonna be driving it for a bit to make sure everything stays cool.
New head gasket, fresh 91 octane gas, and a knock sensor. She's now making 184hp. It's an 18hp gain.
For some reason it's still idling around 1200rpm, so I gotta track that down (confirmed that the IAC is working). Working theory is some sort of vacuum leak, but I haven't found anything yet.
Other than that, it's just gonna be driving it for a bit to make sure everything stays cool.
What kind of IAC is it? I recently had a similar problem and kept closing the throttle with the stop screw. It turned out that the IAC either wasn't advancing or extending enough steps initially (sorry I can't remember which), so it wasn't really covering it's entire physical range. I have mine basically all the way closed when the engine is warmed up, vs active idle speed management. When I figured it out, the thing wanted to idle at 300RPM, so the throttle stop went back out.
So you could try increasing the homing steps or closing steps.
So you could try increasing the homing steps or closing steps.
I don't know much about IAC, but it is a stock Nissan unit.
www.autozone.com
(the extra plug is for A/C on to raise the idle) Not used in my case.
Duralast Idle Air Control Valve AC4063
Shop for Duralast Idle Air Control Valve AC4063 with confidence at AutoZone.com. Parts are just part of what we do. Get yours online today and pick up in store.
www.autozone.com
I don't really know what you mean, but when I get a chance to look it in TunerStudio I'll get back to you if I don't undestand what I'm looking at.
I don't know how that one works. 1-wire on top makes me think it's a PWM-controlled valve. The second thing with two wires, is that a position sensor? It could also be a bypass valve for something like cold-idle step up, or additional air for A/C compressor on. Probably disconnecting either one would do something...
Where do the vacuum lines go?
(my previous post assumed that the ECU was controlling steps of a stepper motor, but that's probably not the case here.)
Where do the vacuum lines go?
(my previous post assumed that the ECU was controlling steps of a stepper motor, but that's probably not the case here.)
I believe it is PWM, I seem to remember that when messing with it last year.
The 2nd part is a bypass valve for the ac compressor.
The part that looks like a vacuum line is the intake. It hooks to a hose that connects to the intake just behind the air filter.
The 2nd part is a bypass valve for the ac compressor.
The part that looks like a vacuum line is the intake. It hooks to a hose that connects to the intake just behind the air filter.
I finally fixed the high idle issue, and boy do I feel like a dumbass. 
In the pic above, the blue arrow points to the idle adjustment screw. I tried adjusting that before, but turning it all the way out had no effect, so I figured the problem had to be elsewhere. After spending way too much time looking for vacuum leaks, I started looking more closely at the IAC. The IAC has it's own intake, so I blocked that off and the idle came down significantly, but it didn't kill the engine. I had assumed that the throttle body was completely closed at idle, but obviously not, so I started looking more closely at that.
The yellow arrow above shows where the throttle is being held open. Once I found it, I realized the problem.
When I was troubleshooting the engine issues last year I had to take the intake on and off several times. I got sick of having to remove the coolant lines that run on the under side and brought coolant up to the throttle body, so I bypassed them. Since coolant was never going up to the throttle body anymore, as far as the throttle body was concerned the engine never warmed up... hince high idle.
All I had to do was remove that cam and spring and after that I was able to adjust the idle with the adjustment screw like you'd expect. I got it set to about 800 rpms now.
If I ever have issues with cold starts, the megasquirt3 ECU is capable of setting the idle higher until it warms up via the IAC, so removing all of that shouldn't hurt me.
In the pic above, the blue arrow points to the idle adjustment screw. I tried adjusting that before, but turning it all the way out had no effect, so I figured the problem had to be elsewhere. After spending way too much time looking for vacuum leaks, I started looking more closely at the IAC. The IAC has it's own intake, so I blocked that off and the idle came down significantly, but it didn't kill the engine. I had assumed that the throttle body was completely closed at idle, but obviously not, so I started looking more closely at that.
The yellow arrow above shows where the throttle is being held open. Once I found it, I realized the problem.
When I was troubleshooting the engine issues last year I had to take the intake on and off several times. I got sick of having to remove the coolant lines that run on the under side and brought coolant up to the throttle body, so I bypassed them. Since coolant was never going up to the throttle body anymore, as far as the throttle body was concerned the engine never warmed up... hince high idle.
All I had to do was remove that cam and spring and after that I was able to adjust the idle with the adjustment screw like you'd expect. I got it set to about 800 rpms now.
If I ever have issues with cold starts, the megasquirt3 ECU is capable of setting the idle higher until it warms up via the IAC, so removing all of that shouldn't hurt me.
I also fixed my temp guage. After extensive testing, I was able to verify that the guage was working correctly, and that the connection to the sensor was good as well. I grounded the sensor and the guage went to full hot as expected.
The problem had to be the sensor, but I had just replaced it with a new one, so I was a bit surprised... until I realized that I bought a sensor for a 2002 Xterra (to match the engine) and not for a 1991 Pathfinder (to match the guage). The sensors looked identical, so I didn't expect there to be an issue, but they came back to different part numbers.
I tested the Xterra sensor cold, and it read 1.8k ohms to ground. The Pathfinder sensor was only 500 ohms cold.
That ended up being the issue. Once I got the Pathfinder sensor installed, the guage works as it should. Hopefully if I ever have an overheating issue again, I'll know about it before I blow a head gasket, or worse!
The problem had to be the sensor, but I had just replaced it with a new one, so I was a bit surprised... until I realized that I bought a sensor for a 2002 Xterra (to match the engine) and not for a 1991 Pathfinder (to match the guage). The sensors looked identical, so I didn't expect there to be an issue, but they came back to different part numbers.
I tested the Xterra sensor cold, and it read 1.8k ohms to ground. The Pathfinder sensor was only 500 ohms cold.
That ended up being the issue. Once I got the Pathfinder sensor installed, the guage works as it should.
Hopefully if I ever have an overheating issue again, I'll know about it before I blow a head gasket, or worse!
Like the 90ohm vs 240ohm fuel level sending units
Because of where I mounted the new coils, I had to have a new A/C line made, then charge the system. It's always had a good A/C system, and it's got a LOT of windows so I wanted to get that working again before summer. Unfortunately, after charging the system, the compressor wouldn't come on, so I must have messed something up.
After looking over the wiring diagram, it looks like there is an A/C relay that is supposed to turn on the compressor. I didn't have the compressor hooked up to it, but I had a constant 12v to the compressor somehow (connected wrong somewhere I guess), and I'm worried that I burned it up.
the arrows "32" and "13" go to the old ECU and just lets the ECU also control the GND side of the relay, so I should be good to connect those 2 together.
I hate digging into wiring.
After looking over the wiring diagram, it looks like there is an A/C relay that is supposed to turn on the compressor. I didn't have the compressor hooked up to it, but I had a constant 12v to the compressor somehow (connected wrong somewhere I guess), and I'm worried that I burned it up.
the arrows "32" and "13" go to the old ECU and just lets the ECU also control the GND side of the relay, so I should be good to connect those 2 together.
I hate digging into wiring.
Pull the connector off the compressor, put 12v on one side and ground on the other, see if the clutch actuates.
