The car made 193WHPon dynojet before the cat install. VTEC was set at 5600and rev limiter at 8500. tuner said I was losing at least 7hp from stock cat. About 3 weeks later the car sat for 10 days while I was away for work. Started it up and had a CEL. It was intermittent and then the car had no top end power. 4th gear was horrible no power in VTEC. Car ran way rich(from limp mode).
couple months later finally able to take it back to tuner. He ran a check and said I had CEL#9 crank position sensor error. Prelude manual says to replace distributor, he cant tune around it and it is pulling timing from top end. I verified this with several sources it is a know problem. No dyno run that day, pointless to do so with CEL.
Replaced the cat and distributor CEL went away, then took it to another tuner(dynapack), I was disappointed with the original guys for a few reasons. car made a pathetic 128 HP base with no power improvement in vtec. He said tables were way to rich and leaned them out. made 12-20hp increase in low cam but could not make any power in vtec even though it kicks in. he set it at 7700 to keep car in low cam to optimize low performance for time being. we had 5 mechanics there and all of us baffled. no matter how he tuned it he could not get vtec power. The car seems much more powerful than 128hp. I dont know, maybe the dyno messed up?
Things we checked...
camshafts no visible damage or scouring.
ran it open header slight power increase cat was fine no clog.
compression test good numbers.
no CELs or errors according to crome software.
I dont know what else to check, car idles fine but I'm going to verify mechanical timing on the engine at the cam sprockets and crank pulley to ensure they are TDC at the same time. If that is good I dont know what else it could be. Someone please solve this mystery! thanks
my car's set up
98 Prelude
CAI
Skunk2 inteake manifold
stage2 BC camshafts springs/retainers
vibrant headers
magnaflow Cat
RSR exhaust
p28 ECU crome tunned
fidanza flywheel (no timing marks)
exedy stage 2 clutch
manual TB tensioner
It sounds like the whole thing went south after you threw a CEL. Even though it went away after replacing the CAT, I'm skeptical this fixed the issue. Your fuel maps are all screwed up still, but I'm not a mechanic so I couldn't tell you how to fix it. I would drive it around town for a few weeks and see if it relearns the fuel maps. It's worth a try before spending more money replacing parts and paying tuners by the hour.
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~Matt http://www.cardomain.com/ride/2928232 Intake: AEM V2 TB: 68mm ProProducts IM: Euro R IM Insulator Gasket: Hondata Header: Hytech knock off with 2.5 collector, ceramic coated Cat: Vibrant 2.5" SS Exhaust: 2.5" SS w/ Magnaflow mufflers Tuning: NepTune RTP w/ Wideband Underdrive Pullies: AEM
^Not sure if a chipped OBDI like his will "relearn" the fuel maps.
I would throw a stock ecu back in and see if it runs correctly.
Your right it should not relearn it doesnt have that ability in OBDI. That said the stock ECU may run the car fine but it will eliminate a lot of my gains especially from the cams. That would be counterproductive in the long run, I need to get the car to run well with the p28.
An update to the issue. twice now I have thrown CEL#7, throttle position sensor. I have cleared it and sometimes it comes back,during cold starts. So I'm undecieded whether or not it is a genuine fault. Called the tuner and he said it did not happen while tunning and even if it did that it would not cause the car to loose 80+HP.They are doubtfull that CEL7 is the real problem here. That said the car feels fine in the low cam, there has been a good increase in power down low, and the leaner mixture has netted better fuel economy
Thanks for the input guys, all ideas do help. This post is a plea to all members for help! Thank you
Your right it should not relearn it doesnt have that ability in OBDI. That said the stock ECU may run the car fine but it will eliminate a lot of my gains especially from the cams. That would be counterproductive in the long run, I need to get the car to run well with the p28.
An update to the issue. twice now I have thrown CEL#7, throttle position sensor. I have cleared it and sometimes it comes back,during cold starts. So I'm undecieded whether or not it is a genuine fault. Called the tuner and he said it did not happen while tunning and even if it did that it would not cause the car to loose 80+HP.They are doubtfull that CEL7 is the real problem here. That said the car feels fine in the low cam, there has been a good increase in power down low, and the leaner mixture has netted better fuel economy
Thanks for the input guys, all ideas do help. This post is a plea to all members for help! Thank you
So why dont you test the TPS to see if its malfunctioning? Hook it up turn the car to on position and ground your black post of the mulitmeter to the battery and put the red post to the red/blk wire and twist the throttle rotor by hand and see if the voltage smoothly changes.
Your right it should not relearn it doesnt have that ability in OBDI. That said the stock ECU may run the car fine but it will eliminate a lot of my gains especially from the cams. That would be counterproductive in the long run, I need to get the car to run well with the p28.
An update to the issue. twice now I have thrown CEL#7, throttle position sensor. I have cleared it and sometimes it comes back,during cold starts. So I'm undecieded whether or not it is a genuine fault. Called the tuner and he said it did not happen while tunning and even if it did that it would not cause the car to loose 80+HP.They are doubtfull that CEL7 is the real problem here. That said the car feels fine in the low cam, there has been a good increase in power down low, and the leaner mixture has netted better fuel economy
Thanks for the input guys, all ideas do help. This post is a plea to all members for help! Thank you
The reason you would add the stock ECU, is to test if it is a fuel map issue. Your tuning may be way off. I'm not suggesting to keep it that way, just trouble shoot.
You need to test the TPS, adjust the voltage, and replace if needed.
using a long ratchet extension we pulled out #1 spark plug and dropped the extention down the hole to rest on the pistion. We hand cranked the engine at crank pulley and the cams TDCed with the highest point of the ratchet extensioin. Arrows straight up and hash marks pointing towards eachother level on the cam sprockets. Pulled out the distrubutor cap and the rotor was pointed at #1. good mechanical timing.
CEL did not come back either, I really doubt there is a true fault with the TPS. I'll be honest I couldnt get a good reading with the multimeter user error, harder than I thought. I will have to get a shop to do it.
With good compression numbers, good timing, and no intake or exhuast problems I'm convinced it is a tunning issue. Is there anything I'm missing?
Going way for 12 days for work so I wont be on for a bit. If anyone gets any ideas while I'm away please post them up, I really appriciate the input here. When I get back its shop time and hopefully the end of this problem.
using a long ratchet extension we pulled out #1 spark plug and dropped the extention down the hole to rest on the pistion. We hand cranked the engine at crank pulley and the cams TDCed with the highest point of the ratchet extensioin. Arrows straight up and hash marks pointing towards eachother level on the cam sprockets. Pulled out the distrubutor cap and the rotor was pointed at #1. good mechanical timing.
CEL did not come back either, I really doubt there is a true fault with the TPS. I'll be honest I couldnt get a good reading with the multimeter user error, harder than I thought. I will have to get a shop to do it.
With good compression numbers, good timing, and no intake or exhuast problems I'm convinced it is a tunning issue. Is there anything I'm missing?
If the CEL came on for the TPS you either need to replace it or adjust it. Get out the multimeter.
unfortunately I do not have the graph to post it, I was so disgusted I did not take it. I have an appointment with the original tuner for friday morning. I will update the thread after that tunnihng session hopefully with a graph and acceptable numbers. BTW CEL only came on 1 in the last week...
Tunning canceled, the CEL is back and stays on, I have cleared it like 12 times and it keeps coming back even when warm. I'm finnaly admiting that the damn things is broken. no more intermittent faults, its here to stay. Priced a new one online for like 80$, auto zone and the like are no help here as they only come with throttle body. Once I get it I gotta install it and set it which is no easy task. The saga continues...
I actually purchased an entire throttle body assembly, map and TPS included. However it hasnt helped solve the problem 100%. The car still regularly displays CEL7 TPS fault during cold starts in them morning. Its about 30-40F in the morning here. Also the car is idling low now at a about 400rpm. Since I have lightened flywheel when the revs drop it sometimes conks out. So I'm adjusting th idle screw to compensate. I dont know whether to send it back for a refund or not. I'm afraid of just buying a TPS by itself because of the calibration involved. So I'm still incredibly frustrated I'm so sick of this project and only want to finish it. Its not like this is a complicated build.
Any ideas on why the CEL comes on during cold starts only. Remember I have OBDI p28 ECU
I actually purchased an entire throttle body assembly, map and TPS included. However it hasnt helped solve the problem 100%. The car still regularly displays CEL7 TPS fault during cold starts in them morning. Its about 30-40F in the morning here. Also the car is idling low now at a about 400rpm. Since I have lightened flywheel when the revs drop it sometimes conks out. So I'm adjusting th idle screw to compensate. I dont know whether to send it back for a refund or not. I'm afraid of just buying a TPS by itself because of the calibration involved. So I'm still incredibly frustrated I'm so sick of this project and only want to finish it. Its not like this is a complicated build.
Any ideas on why the CEL comes on during cold starts only. Remember I have OBDI p28 ECU
YOU NEED TO VERIFY THE TPS VOLTAGE.
Sorry, a few have tried to say this a few times. There are probably other issues, but you need to troubleshoot.
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with no power improvement in vtec. He said tables were way to rich and leaned them out. made 12-20hp increase in low cam but could not make any power in vtec even though it kicks in. he set it at 7700 to keep car in low cam to optimize low performance for time being. we had 5 mechanics there and all of us baffled. no matter how he tuned it he could not get vtec power.
The car seems much more powerful than 128hp. I dont know, maybe the dyno messed up?
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