dukenukem Posted July 10, 2009 Share Posted July 10, 2009 A month ago I dyno'd my '96 RZ-S and scored 219HP at the rear wheels, (266HP at the fly by calc.). The Turbo's were giving 0.56bar on the flat line (stock should be 0.7). I came to the conclusion this was just age (13 years and 60,000 miles) and is to be expected, but with a proper good service and if the turbo's were back at 0.7bar I would be getting close to 300HP. So, I booked my beloved Supra in to my nearest Jap Performance Garage for a major service (Timing Belt, Oil/Air/Fuel Filters etc.) and at the same time tell them to whack it back on the dyno and check for pressure leaks/blocks and anything else that might cause the drop to 0.5bar. They check it out, tell me my car's in excellent condition and they can't find anything wrong. I looked at the dyno results (hoping to see something magical) and it now has 192HP at the wheels!! (236HP at the fly by calc.)... I'VE LOST 27HP AND KILLED MY BANK ACCOUNT IN THE PROCESS!!! So what's the crack with this?? Have they put the timing belt on one tooth off or what? Would this be obvious if I pressure tested the cylinders? The car doesn't quite feel its usual perky self. It still purrs like it should (maybe slighty low on tickover but that could be the new oil) and goes some when you hoof it but does feel like 26HP has gone walkies. It was even a much hotter day when it was first dyno'd. help.... Quote Link to comment Share on other sites More sharing options...
DamanC Posted July 10, 2009 Share Posted July 10, 2009 Something is wrong mate, very wrong. Quote Link to comment Share on other sites More sharing options...
wkdtime Posted July 10, 2009 Share Posted July 10, 2009 (edited) Sounds like Second turbo not kicking in, I had the same problem with my old Supe, search for TTC conversion (Pipe method), this will run the turbos parallel at 4k RPM, it's a good test to show sticky IACV problems (I think thats what they're called) which is what I think your car is suffering from. Edited July 10, 2009 by wkdtime (see edit history) Quote Link to comment Share on other sites More sharing options...
supra matt Posted July 10, 2009 Share Posted July 10, 2009 were both dynos on the same dyno ? as they differ form rr to rr . but your power is low! what's the spec? Quote Link to comment Share on other sites More sharing options...
dukenukem Posted July 10, 2009 Author Share Posted July 10, 2009 I can hear the first turbo whistling away at low rpm and the second definately kicks in at 4,000. The thing is is the boost pressure is near enough the same as before (I will post the graphs when I can borrow someones scanner tomorrow), but it appears the car has lost HP from somewhere else!! [sAD][/sAD] It was on the same dyno by the same people. The car is completely stock (well I did have a TRD oil filter before but it's not like that's going to affect the power!!). Quote Link to comment Share on other sites More sharing options...
Sharpie Posted July 10, 2009 Share Posted July 10, 2009 (edited) Were the air temps different on each of the days ? We have had a hot spell recently. Winter = Cool Air temps, more power but, less traction due to the cold temps on the ground Summer = Warm/Hot air temps, less power but, better traction on the road due to higher temps. Sorry if you already know this. ****** Did the RR operator plug in exactly the same details this time around ? (Different figures will shown different results). Edited July 10, 2009 by Sharpie (see edit history) Quote Link to comment Share on other sites More sharing options...
Fifty Posted July 11, 2009 Share Posted July 11, 2009 reset your ecu? Rich Quote Link to comment Share on other sites More sharing options...
JohnnyW Posted July 11, 2009 Share Posted July 11, 2009 (edited) I would say IACV VSV had exactly the same issue on mine, it does still feel like there's a "kick" at 4,000 rpm because the boost drops down slightly then back up but then you can feel that's there's no real guts to it in the higher revs. Here's my thread on the problem (2nd page is where it's at) http://mkivsupra.net/vbb/showthread.php?t=182441 have a look especially at my shakey boost gaugue video it shows the dip at 4,000 rpm then back to the same pressure. If it's not that then worth having a look at what sort of state your intercooler is in. Hopefully it is the IACV VSV as it's a relativly cheap fix I got one 2nd hand on here but even a new one from Toyota was around £70. Edited July 11, 2009 by JohnnyW (see edit history) Quote Link to comment Share on other sites More sharing options...
Pete Posted July 11, 2009 Share Posted July 11, 2009 Post up the dyno plot, that may help with the diagnosis. Quote Link to comment Share on other sites More sharing options...
AJI Posted July 11, 2009 Share Posted July 11, 2009 leaky intercooler maybe the problem, if not a crack in one of your pipes, or a problem with the VSVs Quote Link to comment Share on other sites More sharing options...
dukenukem Posted July 11, 2009 Author Share Posted July 11, 2009 Here are the graphs. The pdf's are from the first dyno a month ago, run on a warm day. The jpeg's are the second dyno done this week after the car was serviced and the timing belt changed, clearly lost power (on another equally warm day). The turbo pressure is a tiny tiny bit less than before, but this is not my concern. Its the AFR that indicates the car is now running significantly more lean. I'm thinking, if the garage put the new timing belt on a notch out, the injectors could be spraying fuel against the valves as they are closing, rather than opening, hence less fuel getting into the chambers and the higher AFR. I took the car out again last night and it drives absolutely fine. I think if there was one notch out on the timing belt this will only make a subtle difference. Anyway, I'm just guessing it's the timing belt. Fifty says reset the ECU? (sounds nice an simple ). All comments welcome.Boost_Pressure.pdfPower.pdf Quote Link to comment Share on other sites More sharing options...
SteveR Posted July 11, 2009 Share Posted July 11, 2009 Turbo pressure is well down - looks like a leak to me. It's not running lean IMHO. Quote Link to comment Share on other sites More sharing options...
dukenukem Posted July 11, 2009 Author Share Posted July 11, 2009 Turbo pressure is well down - looks like a leak to me. It's not running lean IMHO. Have you compared the AFR graphs before and after? There's a big difference. Yeah, I don't know what the problem is with the turbos. The tuning garage said they couldn't find anything wrong and everything seems to be working fine. The thing is, they're still giving the same pressure as before, but the AFR is completely different and the powers gone down. Quote Link to comment Share on other sites More sharing options...
SteveR Posted July 11, 2009 Share Posted July 11, 2009 No, to be honest I just looked at the latest info. There is a leak there somewhere, I'll put money on it. What condition is your intercooler? Quote Link to comment Share on other sites More sharing options...
dukenukem Posted July 11, 2009 Author Share Posted July 11, 2009 No, to be honest I just looked at the latest info. There is a leak there somewhere, I'll put money on it. What condition is your intercooler? Well....that's a good question. Don't really know TBH. As far as I know its the same one that was with the car when it left the factory and the tuning garage didn't report any problems. Quote Link to comment Share on other sites More sharing options...
SteveR Posted July 11, 2009 Share Posted July 11, 2009 Well....that's a good question. Don't really know TBH. As far as I know its the same one that was with the car when it left the factory and the tuning garage didn't report any problems. Something is leaking. The car should make at least 0.8bar of boost - preferably appraoching 0.9 bar. Get on your hands & knees and look at the intercooler through the driver's side 'nacelle' to the side of the main bumper opening. Quote Link to comment Share on other sites More sharing options...
j1mb0b1 Posted July 11, 2009 Share Posted July 11, 2009 I'am only getting about 0.65/0.7 bar and I'am running TTC, So if there was a boost leak with mine TTC should not work right ? Quote Link to comment Share on other sites More sharing options...
Guigsy Posted July 11, 2009 Share Posted July 11, 2009 TT with less power than an NA :S Quote Link to comment Share on other sites More sharing options...
marc_p Posted July 11, 2009 Share Posted July 11, 2009 Ouch, that's less than my N/A. Fancy a race Quote Link to comment Share on other sites More sharing options...
dukenukem Posted July 12, 2009 Author Share Posted July 12, 2009 Ouch, that's less than my N/A. Fancy a race Are you going to Suprapod? If so, this could be you --> Quote Link to comment Share on other sites More sharing options...
SteveR Posted July 12, 2009 Share Posted July 12, 2009 I'am only getting about 0.65/0.7 bar and I'am running TTC, So if there was a boost leak with mine TTC should not work right ? Whether running TTC or sequential, you should see the same boost pressure when both are up to fully online (so 4,000~4,500 rpm upwards). Worth investigating as you're missing 'free' power. Also an air leak can affect the fuelling, but worse still a bad leak will mean the turbos would be overworking: spinning way too fast as they try to create the required pressure (against little back pressure), which would shorten their life. Quote Link to comment Share on other sites More sharing options...
AJI Posted July 12, 2009 Share Posted July 12, 2009 I found the stock SMIC to be easier to access than I thought it would be. Take off the driver's side wheel arch shroud (well the front part of it is only necessary) and you get a good view of the SMIC,...its not that hard to remove it for a good check around, and perform a pressure test (using a motorbike inner tube - costs about £5) You may find this useful : http://www.mkivsupra.net/vbb/showthread.php?t=184367 Quote Link to comment Share on other sites More sharing options...
caseys Posted July 13, 2009 Share Posted July 13, 2009 Did they not do a leakdown test for you dude to check if your system could maintain 0.8-0.9 bar? Wouldn't think it'd be the timing belt causing this, you'd surely feel it running a little on the jerky side. Quote Link to comment Share on other sites More sharing options...
j1mb0b1 Posted July 13, 2009 Share Posted July 13, 2009 Whether running TTC or sequential, you should see the same boost pressure when both are up to fully online (so 4,000~4,500 rpm upwards). Worth investigating as you're missing 'free' power. Also an air leak can affect the fuelling, but worse still a bad leak will mean the turbos would be overworking: spinning way too fast as they try to create the required pressure (against little back pressure), which would shorten their life. What I mean is if I had a boost leak TTC would not work so I have been told, And it does work but I only get 0.65/0.7 bar not 0.8/0.9 as poeple say you should get as stock ??? Quote Link to comment Share on other sites More sharing options...
SteveR Posted July 13, 2009 Share Posted July 13, 2009 What I mean is if I had a boost leak TTC would not work so I have been told... TBH I'm not familiar enough with the working os the system when in sequential or TTC mode to understand why that would be the case or to comment any further, sorry. /chocolate teapot Quote Link to comment Share on other sites More sharing options...
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