I'd be curious to know what the plugs look like and/or what a monitor shows from the O2 sensors while this is happening. Also, I'm a little concerned about your comment about the car having a new distributor, since these cars don't have distributors.

Here you go. I can't remember, but I think some early 1996s had the 95 style ECU, and later ones had the 96-99 style ECU.https://www.2gnt.com/index.php?d=ECU_Pinout

How are you measuring AFR? Do you have a wideband O2 sensor? Narrowbands will oscillate like what you're describing. Otherwise, putting larger injectors in your car without a way to adjust the base fuel pressure can certainly cause you to run rich.

Is the turbo water cooled? I don't see coolant lines, but that could be adding a ton of heat to your cooling system.

With that many miles and a suspected head leak, I'd rebuild the engine before anything else.

Yes, and yes.

As far as I know, your two options are: 1) fabricate one from scratch, 2) port and polish a stock manifold. There used to be some Chinese-made sheet metal manifolds available. The quality was dubious, and I'm not sure they're still in production.

I agree that threads will strip before the torque affects the bearing. I actually can't find an exact value in the 420A overhaul manual, but the Neon FSM says the bolt should be torqued to 61 N-m (45 ft-lbs).

It's still there. Check this out. You might have to scroll all the way to the bottom.https://www.2gnt.com/index.php?d=ECU%2520Pinout

I've never owned an A/T 420A, but I'm fairly certain all transmission-related fuses are in the dedicated relay/fuse box in the engine bay. It shouldn't be too hard to track down the right one.

Those are great points.

I believe they're the same part for both the 420A DSM and 2.4L PT Cruiser: 04777555AB.

I would replace the whole thing. Welding it will take just as much work (removing the transmission, disassembly, etc.), and depending on who welds it, it will cost just as much, if not more.

You might have gotten this all straightened out by now, but here's what I see:FunctionInternal PinsConnector PinsIAC controlJS0-JS3IACxx12V for IAC controllerJS9 to S12CN/ABarometric pressure sensorJS5N/AGeneric/tach output (5V pull-up)JS11 to pad...

After the car dies, I would check the fuel pressure and look for spark to help start narrowing down potential causes.

You can turbocharge a 420A motor. It has been done many times before. Pre-2007 Evos used the 4G63 motor, which is the same motor used by factory turbocharged DSM's. It will physically fit in a non-turbo 2G DSM's engine bay, but not without a lot of modification. The transmission is not...

Yeah, I wasn't sure if that's just a stock photo or the actual hoses.

What about these?https://frsport.com/samco-sport-tcs400-c-blue-samco-blue-radiator-hose-kit-mitsubishi-eclipse-rs-420-a

I wouldn't say 101 psi, for instance, is a dangerous pressure, but we don't know how high yours is because your gauge can't read more than 100psi. I would guess that it's much higher if the oil filter is bulging. The oil pump is such a critical component, I just wouldn't trust an eBay part for...

I agree that you could probably build your own from discrete components. I would use 1N4007 diodes since their Vrms and If meet or exceed the parameters of the part you have (700V vs. 220V, and 1A respectively). Their Vrrm is a little lower (1,000V vs. 1,300V) but without knowing anything more...

He said "well past 100 psi", which makes me wonder if his gauge only reads up to 100 psi.

I don't usually advocate throwing parts at a problem without tracking down the culprit first, but if it were my car, I'd get a known good oil pump. The Melling M190 is the model that used to be most popular among 420A owners. It goes for $91 on RockAuto as of 4/2021.

Gotcha. Sounds like you have a good handle on the problem then. If you already have a remanufactured head, you should be good to go after you get the head studs, head gasket, and upper gasket kit.

Along with the gaskets and head studs, you might want to consider a new timing belt, tensioner and water pump, depending on how old those components are.Your car is losing 1-2 quarts of oil while it's parked (i.e. engine is off)? Am I reading that correctly? If your cylinder head has a crack...

Did you check the alignment again after tensioning the belt last week? A lot of times it looks like it's aligned until you tension the belt.The belt shouldn't stretch so much that it throws your timing out of alignment by any appreciable amount. Since you have adjustable cam gears, though...

The v3.0/v3.57 boards have two crank sensor input circuits: one originally designed for VR sensors and one designed for Hall effect or optical sensors. The VR circuit is a bit more versatile and works well enough for Hall effect (like in the 420A) and optical sensors with 0-5V+ outputs, so they...

Old post, I know... But while they were certainly assembled in Illinois, but I'm almost certain they were sold in Japan.

Agreed. I didn't mean literally any hose, I meant any fuel injection hose (and any vacuum hose, etc.). It doesn't need to be a particular model or from a particular source.Again, agreed. I was thinking of miscellaneous hardware for mounting things like the FMU, etc. when I wrote that. I do not...

Sorry Tim--like Chris said, it's nothing personal, I'm just trying to stick to a rule we've had in this sub-forum for a long time. We used to have people come here and ask about how to do something, and the threads would often devolve into an argument about if it should be done at all...

Guys, just a friendly reminder that we have a rule about no "sell it and get a 4G63" responses in this forum. The rule is stickied to the top of the forum for your convenience.@angoedaly48, you'll probably get more helpful replies if you post a more specific question. Lots of people have...

I'm not necessarily convinced a vented cap wold fix your problem, but it wouldn't cause any more of a leak than that little red breather filter you have. The crankcase isn't sealed, otherwise the PCV system wouldn't work.

That looks pretty similar to the one I got from RadiatorBarn.com. I just found my receipt, by the way. It cost $120 back in 2006!

Maybe they're just "new old stock" or knock-offs these days, but there are definitely aluminum radiators out there for the 420A.

RadiatorBarn.com used to sell an all metal radiator for our cars. I think they were around $120--granted, that was 10+ years ago, so they would probably cost a little more today. I did a little digging and found that the online component of the company was bought by GetAllParts.com sometime...

The information you're finding is that old because I don't think much has changed since then. I never did the swap, but as far as I know, you'll have to fabricate your own passenger side motor mount and notch a 2.4L oil pan to get it to fit.

Thanks to @motomattx for a great answer. The Wikipedia article on "Top Fuel" also has a nice summary of the technical aspects of these cars. I guess anything's possible with enough time and money, but it doesn't sound remotely practical to me.https://en.wikipedia.org/wiki/Top_Fuel#Top_fuel_engines

This is the one I'd buy if I were in the market for one today:https://www.innovatemotorsports.com/products/mtxl_plus.php

There's not much of an advantage to running aftermarket injectors if the rest of the fuel system is stock. I'd go for an aftermarket fuel controller/EMS or even an FMU/S-FMU before getting new injectors.

I don't think I ever had 14" rims on my car after I upgraded to a rear disc setup, but I found this post from way back in 2005 that claims 14's will fit fine:https://www.dsmtuners.com/threads/2gs-and-15-wheels.206861/#post-1721266Here's another...

I'm not sure if you can find the original stuff anymore. Modern sells the Mopar ATF+4 now. Their product page notes this:https://www.modernperformance.com/product/mopar-transmission-fluid-atf4-neon-srt-4/95-99-neon-drivetrain-transmission

You should be able to use a 95-99 Neon block with your head, that's correct. I believe you can use 00-03 blocks too, with some caveats, but I don't remember the details. As motomattx said, the SRT-4 is a different beast.

I'm sure there are newer options these days, but Walbro 255lph pumps are the old standard: https://walbrofuelpumps.com/255lph-walbro-gss342-intank-fuel-pump.html.html

But they never asked for the caps? What good is it to have just half of the bearing surface machined?

I'm not sure what they could've machined without the caps...

Apparently this guy got his hands on a legitimate programming tool used by Chrysler engineers and can indeed change the values inside these ECU's. To what degree they can be changed, or how effective it is overall, I don't know. He's been pretty tight-lipped about it all, but this is old news...

You can put both the AFPR and FMU in the engine bay, yes.

I would put the AFPR wherever the stock FPR is--it depends on your current fuel line configuration. The rest can stay the same as in the diagram.The only other thing I would add is this: if you're planning on running a return line in a late model fuel system ("configuration #1"), then I would...

I would do that first, then fix your CEL, before doing anything else.

Why not check your timing?

Yes, for future reference, per the page I linked:Updated above for clarity.