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b230ft swap with RSI Stage 1 cam , suddenly no power

whatoctaneiscoffee

now with more caffeine!
Joined
Apr 25, 2020
Location
Maryland
Hello tbrickers, I'm nearing the limit of my own troubleshooting ability and would love your input.

The previous owner of this new-to-me motor had it built before deciding to go a different direction. It's a 1993 b230ft with a ported 530 head and rsi stage 1 cam. I brought it home, gave it some new gaskets, and put it in my 93' 940 wagon. I kept my stock mitsubishi turbo. The car idles fine, wavers a little bit but nothing unreasonable. When accelerating, if I give the car half throttle my boost gauge goes right to 8psi. Full throttle takes it straight to 13, and the kickdown takes it nearly to 20. The engine revs normally, a bit faster than I'd experienced with the stock cam in the other motor, and the aw71 shifts normally. On the drive where I got the above boost numbers my exhaust manifold was glowing when I checked it, centered around the flange. Since then I've driven using no more than 1/4 throttle which keeps boost at 2psi or below, and that's kept my manifold the correct color.

That alone has me concerned, but what really has me scratching my head is that the car is also painfully slow. Past that 1/4 throttle rpm and psi keep increasing but the car doesn't move any faster. I can't find any vacuum leaks, I've checked and re-checked my timing, tried adjusting the cam backwards and forwards, all to no avail. Transmission fluid looked a little dark, so I drained and refilled it and have a new filter on the way. I'm fitting a wideband tomorrow. Anything else I should check?
 
FYI glowing orange after driving is normal. That's a lot of heat converging in a small area. I wouldn't be ok with the boost going over 12pdi with the mitsu turbo. You're just making hot air. I'd suggest checking the catalytic converter making sure it's not clogged up and restricting the exhaut flow.

The other thing that can happen is the air intake hose from the air mass meter to the turbo can get sucked shut which will make your car slow or even cut out. If that hose is soft then it's definitely suspect.
 
FYI glowing orange after driving is normal. That's a lot of heat converging in a small area. I wouldn't be ok with the boost going over 12pdi with the mitsu turbo. You're just making hot air. I'd suggest checking the catalytic converter making sure it's not clogged up and restricting the exhaut flow.

The other thing that can happen is the air intake hose from the air mass meter to the turbo can get sucked shut which will make your car slow or even cut out. If that hose is soft then it's definitely suspect.

I'll definitely give that hose a check, thanks. The car doesn't have a car at the moment, it's 2.5in pipe from the turbo all the way to the muffler. Would porting the flange on the manifold help?

The car was set to 12psi before this swap, I'm only seeing these numbers now and believe me I'm not comfortable with them. I'll definitely dial it down once I figure out what's causing my issue.
 
You can check out the pictures on stealthfti pbase page for examples of porting the flange for the turbo on the exhaust manifold. https://pbase.com/stealthfti/miscellany

Even at 12psi if the intake air hose is soft and compromised it can be sucked shut but that usually is a sudden loss of power.

It may be one of those situations where the small turbo is not good enough flow for what the engine can produce for airflow. Especially on the top end. I've read here about that happening.
 
Retarded timing?

Late spark timing will have fuel burning in the exhaust.
Great for making boost! But will make your exhaust manifold look like a lava lamp!

20psi on a Mitsu!!!!? I would not have guessed that little thing would push that much!
Definitely way outside it's happy place, I would also venture that if the motor made any power like that it would probably have disassembled itself.
It appears it is not making enough power to hurt itself.

If setting spark timing correctly does not fix it, it's time to get out the degree wheel and check the cam timing and the marks.
The balancer or belt may have slipped and you are in LaLa land.
 
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You can check out the pictures on stealthfti pbase page for examples of porting the flange for the turbo on the exhaust manifold. https://pbase.com/stealthfti/miscellany

Even at 12psi if the intake air hose is soft and compromised it can be sucked shut but that usually is a sudden loss of power.

It may be one of those situations where the small turbo is not good enough flow for what the engine can produce for airflow. Especially on the top end. I've read here about that happening.


Popped the hood and worked the throttle by hand while watching that hose, it's not collapsing. Unplugged the maf and the car started running very rough so the sensor is still working. I didn't have a can of carb cleaner handy, I'm going to grab one and clean up the ptc element and iac. Don't know if those being dirty or faulty would cause this but why not make em shine? I also took the car for a short drive and discovered it stumbles if you mash the throttle. Feels steady if you roll onto the pedal, but there's a strong moment of hesitation with sudden changes in throttle input.

The wideband afr will be going on after work, I'll take it for a drive around the block and see what numbers I get. I'll redo the timing again just to be safe.
 
Retarded timing?

Late spark timing will have fuel burning in the exhaust.
Great for making boost! But will make your exhaust manifold look like a lava lamp!

20psi on a Mitsu!!!!? I would not have guessed that little thing would push that much!
Definitely way outside it's happy place, I would also venture that if the motor made any power like that it would probably have disassembled itself.
It appears it is not making enough power to hurt itself.

If setting spark timing correctly does not fix it, it's time to get out the degree wheel and check the cam timing and the marks.
The balancer or belt may have slipped and you are in LaLa land.

So far I've been setting piston 1 at tdc the old fashioned way through the spark plug hole, I've heard the mark on the crank pulley can spin and I don't trust it. The degree wheel might be the way to go, I've used the mark on the cover, the string method, and looking at the cam lobes with the valve cover off. Does the aux shaft gear on this motor influence timing? I was under the impression it was only powering the oil pump since my distributor is on the cam, and that the rotation of the distributor doesn't matter as lh2.4 self adjusts.

20 psi was definitely beyond the mistu's happy place haha, only saw that number once on a test drive. I wanted to make sure I was actually having a problem instead of just being outside the power band of the new cam.
 
Popped the hood and worked the throttle by hand while watching that hose, it's not collapsing. Unplugged the maf and the car started running very rough so the sensor is still working. I didn't have a can of carb cleaner handy, I'm going to grab one and clean up the ptc element and iac. Don't know if those being dirty or faulty would cause this but why not make em shine? I also took the car for a short drive and discovered it stumbles if you mash the throttle. Feels steady if you roll onto the pedal, but there's a strong moment of hesitation with sudden changes in throttle input.

The wideband afr will be going on after work, I'll take it for a drive around the block and see what numbers I get. I'll redo the timing again just to be safe.

You won't see that hose collapse with no load on the engine.
 
Can you do a leakdown test on each of the cylinders at TDC? I had similar symptoms and it turned out to be a burnt exhaust valve. It was leaking un-burnt fuel into the manifold where it worked like an anti-lag.
 
Timing is not adjustable on LH2.4, since it's driven off the crank sensor.
The aux shaft does nothing other than drive the oil pump.
Have you checked that the cam timing is correct? Pull the cover, make sure the dowel pin hasn't sheared on the cam, timing marks line up, all that.
A stumble when you mash the gas but fine when you roll into it makes me suspect either vacuum leak or fuel supply issues. Both pumps in good shape? Good pressure and volume? Vacuum line connected to the FPR? No fuel smell from said vacuum line? Fuel filter been replaced this decade?
There's also the usual stage 0 stuff, vacuum leaks anywhere, plugs/cap/rotor/wires in good shape.
 
were those RSI cams regrinds or fresh? i learned way too late about having to time a regrind differently, and had a scenario reminiscent of this post.
 
Long overdue update, but some progress(?) has been made.

Wideband afr went on and is reading very lean. Added a fuel pressure gauge, checked both my pumps and replaced my fuel filter. Everything there checks out. Plugs look a little white so I ordered new ones, the #4 wire goes all the way on the plug but doesn't click in place so I've ordered a new set of wires as well. Cap and rotor were purchased new with the motor. Went over all my vacuum hoses looking for holes, cracks or blowouts and can't find anything. Checked and cleaned my cbv and confirmed that my wastegate actuator is still working.

I did some more reading on the RSI stage 1 and found that it has very similar specs to a K cam, which is said to make the b230 an interference engine. I'm worried now that while adjusting timing I wasn't as careful as I should've been and have bent my valves. Going to cross my fingers and break out the compression tester. Any other ideas before I pull the head? I was hoping that the next time I ordered a head gasket it'd be to celebrate getting arp studs, not to potentially replace valves.......
 
I don't think it's possible to get the cam timing far off enough to bend valves and still have the engine able to run. It'd probably idle like total trash if you messed anything up that bad anyway.

How lean? Try a spare maf? I don't think any vacuum/boost leaks would make it run lean when you're in the throttle.
 
Back again for another long overdue update.

Compression test came back at 160psi across all 4, so I don't think I've bent any valves. For what it's worth I poked a bore scope through the spark plug holes too and didn't see any marks that indicated a smooch from the valves. So I'm thinking we're good there.

My afr stopped reading as well, I believe the sensor might be bad. So with that out of the picture I put the new plugs and wires on to see if anything changed. No difference, but after a 5 minute drive that was very easygoing all 4 plugs where white - very lean. I had green giant injectors and a 3" maf waiting to go in once I got this sorted out, so at this point I put them in to see if the additional fuel would help this strange lean problem.

Left the battery disconnected overnight, drove it for the first time this morning and while far from perfect, it's much better. Idle sits steady at 1100 and sounds much healthier. Has a small stumble that almost feels like turbo lag when you first get going from a stop, but after that it actually pulls. Past 4psi still doesn't seem to make too much of a difference in feel and it doesn't want to go much faster that 65 without sitting at a few pounds of boost. The shift from 1-2 is very hesitant as well, which makes me think the kickdown cable might be causing some trouble. Luckily I have a replacement cable sitting on a shelf.

My current thinking is that the higher lift and duration of this cam is spinning that poor little 13c so fast that I was really leaning out with the stock injectors. The stock manifold and downpipe might be restrictive enough to contribute to this as well. I've heard that the fuel pressure regulator for a 92' dodge daytona turbo is a drop-in replacement that flows higher that my stock one, if I can track one down I might give that a try. I'm also looking at milling my stock manifold.
 
The issue has been resolved - to anyone having a similar issue, your transmission might be saying farewell. I changed my filter, installed the new kickdown cable and followed ipd's instructions for a flush. 12 quarts later my fluid looked like new and the car was finally moving like it should. This lasted a day before there was a horrible series of noises that gave me a shifter full of neutrals.

Thank you all for your advice and answers. Currently deciding if I want to replace the aw71 or start gathering parts for the t5 swap I wanted to do eventually. Cheers
 
Bump with new information:

Finally got the aw71 out and am in the process of replacing it with a t5. I haven't opened up the transmission yet, but I got quite the surprise from the flexplate. It had sheared off completely around the bolts making a perfect little donut. The input shaft of the aw71 looks unharmed, and I don't see any leaks or ruptured seals. Anyone know what could have caused a failure like this? This car was a daily driver, not a neutral dump burnout machine. I'll make a thread about the t5 swap once that's all buttoned up, but would like to put my mind at ease and find out what caused this so I don't accidentally cook the new transmission.

Link to picture of the damage, since I don't think I can attach images yet: https://www.instagram.com/p/CdjttjZOdEB/?utm_source=ig_web_copy_link
 
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