204bhp at 18psi! HELP!!!

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204bhp at 18psi! HELP!!!

Post by MR2T_Jake »

Hi all, me again...

As many know, I have been getting almost no luck with my MR2...

Further to my last post, I found that my downpipe has a crack in it and that my o2 sensor was totally shot! I have replaced the sensor and wired it in correctly, which has removed 2 stored codes (21 and 25)

I am currently in the process of waiting for my new downpipe and a replacement turbo, which I hope to put on soon. But i want to pick some brains about the power i was seeing before...

204bhp at the flywheel at 18psi boost!?! We all know this really is not right and i am not 100% sure if it is down to the bad o2 sensor at the time or something deeper? My base timing is 10btdc and i would hope the mechanical timing is all correct, a little harder for me to check, unfortunately.

Hopefully the dyno print out shows in this thread for you all to take a look at and give opinions on!

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I can't figure out how to put in an image here, so this is my cry for help. :confused1:
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Re: 204bhp at 18psi! HELP!!!

Post by jimi »

Your image is to small/low resolution to read properly
What were the WHP figures ? flywheel figures (unless done on an engine dyno) are just an estimation (to put it another way a guess)
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Re: 204bhp at 18psi! HELP!!!

Post by MR2T_Jake »

I do not have the WHP figures to hand as they printed in flywheel after the computer conversion. Regardless of this its still way too low for a Turbo at 18psi...
I can't figure out how to put in an image here, so this is my cry for help. :confused1:
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Re: 204bhp at 18psi! HELP!!!

Post by MR2T_Jake »

jimi wrote: 26/07/21 14:28 Your image is to small/low resolution to read properly
What were the WHP figures ? flywheel figures (unless done on an engine dyno) are just an estimation (to put it another way a guess)
176whp, just found that number on my dyno sheet.
I can't figure out how to put in an image here, so this is my cry for help. :confused1:
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Re: 204bhp at 18psi! HELP!!!

Post by MR2DI4 »

The Dyno not only shows up faults but its a picture as to the overall condition of the engine.

It really could be down to the fact the engine is simply stuffed.

Things like compression, crud on the inlet valves stuffing the flow and in general its totally worn out and needs a rebuild.

If the static timing is correct with the 2 pins in the diagnostic box shorted then that's the timing sorted.

What condition are the spark plugs in ? grey ? tan brown ? covered in oil ? black ?

Its just not reasonable to get new power levels out of a 30 year old engine.

Personally I would NOT keep thrashing it on a Dyno because its going to go bang, either just drive it or get it rebuilt.

A replacement turbo ? your barking up the wrong tree if yours is already maintaining 18psi.

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Re: 204bhp at 18psi! HELP!!!

Post by nick »

MR2D14 is correct.

Check engine basics, compression .plugs timing etc. There is over emphasis on boost pressure.

Interestingly my n/a at 80000 miles gave 178bhp, so age is not necessarily a factor.
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Re: 204bhp at 18psi! HELP!!!

Post by MR2T_Jake »

The engine is a fully rebuilt and forged gen2... So compression isn't an issue as they are 175-185psi

My next guess is the mechanic who assembled the crate short block with a new head etc didn't time it quite right?
I can't figure out how to put in an image here, so this is my cry for help. :confused1:
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Re: 204bhp at 18psi! HELP!!!

Post by jimi »

I found that my downpipe has a crack in it and that my o2 sensor was totally shot!
There's every chance that these faults caused the problem, it's almost certain that the the ECU would react to the faulty sensor, it quite possibly switched to safe mode map, restricting timing/fuelling etc.
Until you replace the downpipe and get it back on the dyno and see what you get then I don't see any point in trying to guess what else MIGHT be causing a problem, serves no useful purpose IMO ;)
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Re: 204bhp at 18psi! HELP!!!

Post by MR2DI4 »

Putting the timing belt back on in the wrong place is a pretty common fault.

I would be checking that out as a possibility as well. The cam timing marks are terrible on the MK2, I didn't even know where they were on the car when I fist changed the belt but because it had never been changed, I marked the cams up top with a permanent marker before removing the belt with no1 cylinder at TDC on the timing mark on the crank pully. The marks were still there and correct when I changed the belt the second time.
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Re: 204bhp at 18psi! HELP!!!

Post by MR2T_Jake »

i have been informed it is possible to check timing by taking valve cover off. i will be ordering a gasket and do this one weekend as its probably the easiest way to check on a gen2 3sgte while in the car :)
I can't figure out how to put in an image here, so this is my cry for help. :confused1:
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Re: 204bhp at 18psi! HELP!!!

Post by MR2DI4 »

MR2T_Jake wrote: 28/07/21 14:49 i have been informed it is possible to check timing by taking valve cover off. i will be ordering a gasket and do this one weekend as its probably the easiest way to check on a gen2 3sgte while in the car :)
Not 100% sure you can see the marks with just the cam cover off.

The plastic cam belt cover has a single bolt in the middle of it you cannot get to unless you take the engine mounting bracket off first and thats a lesson in origami because its hard to get out. You need to jack the engine to alter the angle to get it out.

I got so wild with it I ended up smashing off the center mount of the cover so now mine doesn't have a bolt in there and it really doesn't need one either just to hold a cover on. I just blanked the hole in the cover with a bit of Aluminum plate.

The engine in the MR2 is really not that much fun to work on in the car, from cambelt change to alternator change it tests your patience.
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Re: 204bhp at 18psi! HELP!!!

Post by MR2T_Jake »

I have been told by some builders that the cams themselves have tdc notches on them inside the valve cover aswell as the front cam caps which you can use to see tdc without messing around with the mounts to view.
I can't figure out how to put in an image here, so this is my cry for help. :confused1:
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Re: 204bhp at 18psi! HELP!!!

Post by SonicSW20 »

MR2DI4 wrote: 29/07/21 17:50
MR2T_Jake wrote: 28/07/21 14:49 i have been informed it is possible to check timing by taking valve cover off. i will be ordering a gasket and do this one weekend as its probably the easiest way to check on a gen2 3sgte while in the car :)
Not 100% sure you can see the marks with just the cam cover off.

The plastic cam belt cover has a single bolt in the middle of it you cannot get to unless you take the engine mounting bracket off first and thats a lesson in origami because its hard to get out. You need to jack the engine to alter the angle to get it out.

I got so wild with it I ended up smashing off the center mount of the cover so now mine doesn't have a bolt in there and it really doesn't need one either just to hold a cover on. I just blanked the hole in the cover with a bit of Aluminum plate.

The engine in the MR2 is really not that much fun to work on in the car, from cambelt change to alternator change it tests your patience.
He's not talking about the cam gear cover. The cams themselves have notches on them that can be used for timing:

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Re: 204bhp at 18psi! HELP!!!

Post by MR2DI4 »

Good to know never knew that. Still despite that it still gets stuffed up. One or both of the cams "walk" the second you remove the belt so it's very easy to end up with one tooth out.

I found getting a new belt in was a 2 person job you simply don't have enough hands to get the belt on in the right place and that hydraulic tensioner needs to be pushed hard by someone to get all the slack out of the belt while you nip the bolt on it up before pulling the pin.
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