sr20det running wierd/slow after 40+ minutes of driving.

[koukidough]

Okay my s14 with redtop sr20det runs great, but after running it over 40 minutes I start to lose power. It really does not matter if I rev it hard or drive normally. It just looses power after around 40 minutes or so I don't know why. For example... at a stop light going into first gear pressing on the gas I will hear my turbo spool at around 2.5krpm and up then wastegate sound thereafter but no pickup at all. Sounds like nothing is running but the turbo, my whole car feels like a loss of about 40% power. Second gear, same thing. Thid gear will get it to normal sometimes but not always. Anyone know whats going on?

[ILikeMy240sx]

Loss of power... I can think of few things

Check TPS make sure they are to spec.Check timing.Check for vac leaks.Id pull the plugs out and inspect them to see what they look like... this will tell you if for some reason you are running pig rich.

[koukidough]

could it be my turbo dying? I checked all those above and they all seem fine. I have a feeling that its caused by my turbo getting hot. Not sure. I checked the play and it seems fine, doesnt go in and out. It does however move up and down but only if I apply alot of finger pressure to it. There is also a bit of oil in my hotpipe, but that has always been there.

[Jjona5]

When it is running poorly after 40 minutes try removing your gas cap. If you hear a rather loud whoosh and it starts running correctly again you know where to look...

[travisn]

wow, i never thought of that... my car kinda acts like described... but mine only bogs down above 0psi when it is running like crap

[Jjona5]

Yeah you would be surprised how many times that could be the problem. You could also have an exhaust or intake leak. When the car has been running for a while the metal tends to expand and cause problems...

[nonvtecaccord]

When it is running poorly after 40 minutes try removing your gas cap. If you hear a rather loud whoosh and it starts running correctly again you know where to look...

what does this mean?

[ETTInnov04]

Are you by any chance running a FMIC?

[travisn]

i think i have a front mount
Modified by travis newberry at 9:34 PM 6/19/2006

[xero1]

do a fuel volume and pressure test

[travisn]

pressure is ok, dont know how to do volume... i have a walboro 255 and new filter... it hasnt done if for 4 days then it just did it today... dammit, i forgot to check the fuel cap...

[koukidough]

dammit I thought I fixed it after I redid the vacuum hoses. It didnt do it for 6 days. Now it came back, just once though. The possibility of the metal expanding with high heat may have caused a leak somewhere maybe. Well I am going to tighten everything a bit more and see whats up.

[Cyberkreig]

sounds like major heat soak.

[Jjona5]

If you hear a rather loud whoosh that means your cap(if its supposed to be ventilated) is bad or your vent/fuel return lines are working improperly.

[tiger]

Hey, only thing I can think of is that something is getting hot...

[ReD*PiG]

Hey,my car makes the loud woosh sound when I go to get gas when its real low on gas.If it does it when I have a good amount of gas it could mean that my gas cap is shot?My car seems kind of sluggish also as of late.But I also found out that my TPS is shot!I have one on the way from a fellow member.What are the symptoms of a bad TPS?I had a friend test mine and it was reading 12.0? at idle,and when we went to go WOT the number decreased.Normal TPS should read .49 then go up when you go to WOT,is this correct?Thanks......

[travisn]

heat soak to and from where???

[95lstegman]

I have one on the way from a fellow member.What are the symptoms of a bad TPS?I had a friend test mine and it was reading 12.0? at idle,and when we went to go WOT the number decreased.Normal TPS should read .49 then go up when you go to WOT,is this correct?Thanks......

your friend needs to learn how to test a TPS. he was taking a reading from the wrong wire. try the white one next time. and yes, idle voltage should be 0.45-0.55V.

[ReD*PiG]

I'm pretty sure he was testing the right wire,because he tested his then tested mine right after.His read fine he showed me the numbers on the fluke.but mines reading 12.?

[xero1]

how much gas do you have in the tank when the problem occurs?

[95lstegman]

I'm pretty sure he was testing the right wire,because he tested his then tested mine right after.His read fine he showed me the numbers on the fluke.but mines reading 12.?

well maybe he's not experienced at it. i've never seen a bad TPS read 12V unless you get the wrong wire. test it again, and test all the wires. the one reading 0V or 0.2V or so is the ground, the one reading ~12V is the power, and the white one is the feed and should read 0.5V-4.5V. the last SR TPS i saw go bad had a problem with the space in between. it would go from 0.5V to 3.0V all at once near the end of its play.

[ReD*PiG]

Ok,I'll test it again,what are the symptoms of a bad TPS?

[koukidough]

a little less than one fourth. What would it be? My fuel cap or pump?

[travisn]

i dont think it is the tps for either of us bc the problem isnt constant... i think it is heat soak... my car was acting up saturday night, just normal driving... and my turbo was hot (950 for the turbo, 500 for the manifold, and 250 for the block at the exhaust ports) idk why or how it gets hotter at the turbo. but my turbo was just rebuilt, so idk what it could be. but what i do know is that my car runs rich when it is acting up.

i hope that helps with figuring this out...

[travisn]

next time it does it pay attention to your boost gauge, does the problem only occur when you make the engine go above 0psi??? bc that is when my car does it. and if i keep it under 0psi it drives good (when it is acting up, not all the time)

[Cyberkreig]

Walbro pumps get hot, and they are cooled by the fuel around them. When running with less than 1/4 tank of gas the walbro pump builds up heat and as a result fuel pressure declines.

[ReD*PiG]

very interesting,would that also effect the idle though(after pushing in clutch)?

[95lstegman]

i dont think it is the tps for either of us bc the problem isnt constant... i think it is heat soak... my car was acting up saturday night, just normal driving... and my turbo was hot (950 for the turbo, 500 for the manifold, and 250 for the block at the exhaust ports) idk why or how it gets hotter at the turbo. but my turbo was just rebuilt, so idk what it could be. but what i do know is that my car runs rich when it is acting up.

i hope that helps with figuring this out...

1) block and exhaust ports are aluminum and both cooled by the water jacket. they won't be much hotter than your coolant.2) as for the turbo vs. manifold, the exhaust gas gives power to the turbine wheel not only by flowing past it, but also by giving up heat to it. the turbo takes a lot of power simply by absorbing heat from the exhaust gas. so it heats up a lot more than anything else.

the ignitor chip doesn't like heat soak, BTW. it will retard the ignition when it gets too hot, and make the car slow and probably run kinda crappy.

[travisn]

well how to i remedy this?? maybe take the coil cover off?? and ignitor chip... is that the thing that is inline and has a bolt hole at each end? well that is not even close to any heat, at all...

i just temp-ed it today too... mani 500 turbo 900... but this time it was running damn good... side note, what approx speed is 5th gear at 5k? i need that 180mph speedo that some company makes... boy was i cruisn. had to be like 125-135

[koukidough]

okay I just bolted the ignitor chip to my chassis and now it runs a bit smoother. But I still get that same problem when its very hot outside 90f+ also I don't think its the fuel pump cuz I filled it all the way up and it still happened.

O yea Travis,Yes driving it at 0 boost will run fine when the problem occurs anything over 0 boost will cause major power loss and lag. Another thing to take note; when losing power I can hear my wastegate release early at around 1.5k-2.5k rpm. I was testing it just today by pressing on the trottle a little (1cm) and releasing it right away will cause the wastegate to release early. I can repeat it nonstop on and off and hear the wastegate fully open and close in the same rhythm.

Step on throttle=openTake foot off throttle=closeme thinks wastegate may be the culprit. Maybe it gets stuck or loose when extremely hot.

Modified by koukidough at 5:34 AM 7/3/2006
Modified by koukidough at 5:37 AM 7/3/2006