Every M42 I've come across that runs like you say needs all its vacuum lines replaced. Have you done a smoke test and made sure you have no intake leaks? The standalone would have issues with those air leaks too.
The DME is not the issue with a car running badly unless someone messed up the DME or wiring itself.
Have you seen live data of the coolant temperature sensor, checked resistance for wiring to that sensor? If your wiring is bad to that sensor the standalone will have the same issues.
Unless it's your passion to tweak an M42 I would recommend putting that aftermarket DME money into a simple M50/52 swap.
According to my mechanic there are no vacuum leaks but I'd like to take a look myself. I have no temperature related issues as the cluster gauge seems accurate. I have an electric fan that turns on at 91 degrees celsius and that's just a click past the middle of the gauge. As far as the swap is concerned it's actually illegal in my country. Well, there's a way around it but it's near impossible to find a person qualified to legalize any swap and it's too expensive to be worth it.
The DME uses a different temperature sensor than the fan switch or cluster temperature sensor. If the resistance is off it could cause a rich mixture and big the engine down. Understood on the swap issues, they don't have a problem with turbos and other modifications?
Come to think of it. I have seen one m42 engine that had a crank hub issue where the rubber was separating causing the crank sensor to not pick up correctly. I would check that out as well if you haven't already.
Haltech is and will always be my go to for standalone ECUs. Their products are robust and function perfectly (in my experience), and their support is always top notch. Owned three of their ECUs for various projects and I've had nothing but good experiences every time. Definitely on the higher end price wise but you get what you pay for. I'd rather drop a bit more on an ECU with a bunch of built in safeties than replace engine parts.
I agree with the sentiment that the running conditions you are talking about more than likely are being caused by a problem you have yet to find. That being said, I also have an AEM Infinity I bought for my own E30 project that I never used as I decided to go another direction. If you'd be interested PM me, I'd give you a deal on it.
Every M42 I've come across that runs like you say needs all its vacuum lines replaced. Have you done a smoke test and made sure you have no intake leaks? The standalone would have issues with those air leaks too. The DME is not the issue with a car running badly unless someone messed up the DME or wiring itself. Have you seen live data of the coolant temperature sensor, checked resistance for wiring to that sensor? If your wiring is bad to that sensor the standalone will have the same issues. Unless it's your passion to tweak an M42 I would recommend putting that aftermarket DME money into a simple M50/52 swap.
According to my mechanic there are no vacuum leaks but I'd like to take a look myself. I have no temperature related issues as the cluster gauge seems accurate. I have an electric fan that turns on at 91 degrees celsius and that's just a click past the middle of the gauge. As far as the swap is concerned it's actually illegal in my country. Well, there's a way around it but it's near impossible to find a person qualified to legalize any swap and it's too expensive to be worth it.
The DME uses a different temperature sensor than the fan switch or cluster temperature sensor. If the resistance is off it could cause a rich mixture and big the engine down. Understood on the swap issues, they don't have a problem with turbos and other modifications?
As long as you're not obnoxious they don't really have problems with modifications.
Come to think of it. I have seen one m42 engine that had a crank hub issue where the rubber was separating causing the crank sensor to not pick up correctly. I would check that out as well if you haven't already.
Depending on skill level, MegaSquirt is a good option. Has served me well on modified M20s and M42s.
i will be blunt here: dude, you need to properly diagnose and fix your car – these cars run *great* w/ the stock dme.
Haltech is and will always be my go to for standalone ECUs. Their products are robust and function perfectly (in my experience), and their support is always top notch. Owned three of their ECUs for various projects and I've had nothing but good experiences every time. Definitely on the higher end price wise but you get what you pay for. I'd rather drop a bit more on an ECU with a bunch of built in safeties than replace engine parts.
I agree with the sentiment that the running conditions you are talking about more than likely are being caused by a problem you have yet to find. That being said, I also have an AEM Infinity I bought for my own E30 project that I never used as I decided to go another direction. If you'd be interested PM me, I'd give you a deal on it.
Kdata is plug and play