Power Drop after hard run.

I really need some ideas for a troubleshooting list for which could be causing this problem that I can just tick off.

After a bit of freeway driving getting the engine temp up, I went for a hill cruise, nothing too heavy. Pushed into VTEC a few times and the engine was running 100%! I slowed up through a short built up area, then once in the clear opened it up to 7000-8000 to reach the 80km speed limit, I think quickly went through the gears into 5th to climb a decent sized hill but nothing too much for 5th @80km. and the engine was laggy as all buggery, NEEDED 4th just to get up it.

Then the problem went away engine ran fine again. Gave it a bit of a push to try and get it to screw up again, sure enough it did, this time it would struggle to accell from 70-100 in 5th on flat road.

On my way home, i tried reseting the problem by switching the engine off... and it worked for a short time. I tried it a second time at a set of lights, when i went to start it, The engine check light stayed on and the fuel pump wouldn't switch on to prime the engine. I tryed a couple more times and the light went out and the pump primed.

This is 100% an electronic problem because the car runs so perfectly then just cuts into a sort of limp mode, but no ECU check light which i dont understand!

It used to have a hunting/idle problem but I have fixed that and now its just this total lack of power after fairly hot running.

ANY ideas would Be GREAT!

Thanks in advance

Nick

what are your leads like

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Originally Posted by SIKCVC

On my way home, i tried reseting the problem by switching the engine off... and it worked for a short time. I tried it a second time at a set of lights, when i went to start it, The engine check light stayed on and the fuel pump wouldn't switch on to prime the engine. I tryed a couple more times and the light went out and the pump primed.

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This happens sometimes if you turn off the ignition then back on too fast.. it kinda startles the system and it spit's the dummy.. as you found out, just give it a minute and she'll be OK..

as for your drop in power, when you comming DOWN hill, yout thottle is shut thus not letting in much cool air, therefore the intake manifold and TB will soak up a LOT of heat from the Motor that usually is dispersed by the constant flow of cool intake air through an open throttle.

a HOT intake manifold and intake can drastically effect the 'power' of your engine, and if the intake air is hot, the motor will run leaner which can be less 'power' again..

now as ECU man has correclty asked about your leads.. well a tired ignition system, over advanced timing, or even retarded timing, fouled plugs or work leads can also cause a drop in power. add heat into the equasion from some hill driving, and you end up with big drops in power.

Ok, please read my example of what had happened. It was running fine for ages, then I opened it up and it took it fine, then it cracked it. It cracks it after hard running. I let it settle and then it was fine, i ran it hard and it cracked it again.

At the lights I let it sit for about 3 mins before i tried to restart it and THEN it screwed up. It wasn't a quick on off type thing, I've seen quick on off type things, the engine can even tick over on compression and start up if you're quick enough.

The timing has been checked
The leads are good (cant be leads anyway because its an intermitant problem)

Its not a heat thing because I'm not talking 10kwts I'm talking 30%+ power loss. at LEAST 30-40kwts.
Its like driving a Gli civic when it craps out on me.

My thoughts have been
Fuel pump, either surging or failing.
Screwed up sensor (hasn't been found by BLKCRX or wardwhile motors because they havn;t replicated the problem)
Injector problems.

thanks for the ideas though guys, hope what I added will illiminate things.

Need help fairly bad guys... any ideas?

i had kinda similar things before and it turned out to be dizzy problems.

the car would driving fine until i gave it a good revving then the power would die down and sometimes stall :o

might be worth checking out... what was the actual problem? because physicly the dizzy cap looks fine.

get someone to look it over. stock civic ? sorry i dunno what car u run =P..

i never really except many cars to accelerate fast in 5th gear =P..

Its a stock SiR with Intake and Exhaust mods.

Its not a matter of it just not acceling fast... its a total power loss of around 30-40kwts.

I've had a few top mechanics check it over and cant find the problem because it cant be replicated without driving for some time.

well i dunno if you havent already tried but umm u talked to pornstar yet ? or have it looked over by him?

I've had it checked out by James (BLKCRX), Wardwhile motors and ART.

well i dont know much about cars really but its always nice to have more people look at your car to see the problem . i would seriosly say give pornstar a Pm..

A quick note, could it be a coolent temp sensor malfunction at high temps? I checked it out and the wirers wern't in great condition and the clip that goes on the sensor itself was soaked in oil... anyone know if oil becomes conductive at high temps?

check main relay (fuel and spark relay) may get overheated and need replacing / resoldering. Also check dizzy cap , rotor , ignitor unit or internal coil too....all can be affected by heat ( and are common to show similar problems to what you are describing.

good luck !

good luck finding the prob mate. don't u just hate it when u know something is wrong with your car, but u don't know what it is and mechanics can't find the prob. or even worse, some don't even know what u are talking about!

what am i checking for with the dizzy compenents. They all look brand new as the dizzy seems fairly new as it is.

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Originally Posted by SIKCVC

A quick note, could it be a coolent temp sensor malfunction at high temps? I checked it out and the wirers wern't in great condition and the clip that goes on the sensor itself was soaked in oil... anyone know if oil becomes conductive at high temps?

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ECT sensor tells the ECU how hot the engine is - if this sensor sends a bad signal eg "engine cold" whilst engine is hot - the ECU will be putting too much fuel in and it will run too rich.

i'd saw swap the sensor and make sure you resolder the wires.

the ECT sensor is the one with a proper plug - hte egine coolant gauge sensor is smaller and only has one prong.

also do a tune up, dizzy cap and rotor, if not recently replaced...

oh - pics of engine bay would be good!

what oil is this? engine oil? or is it grease? anyway, neither should conduct. temp sensor malfunction should turn up with a check light i would have thought.

Quote:

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Originally Posted by SIKCVC

A quick note, could it be a coolent temp sensor malfunction at high temps? I checked it out and the wirers wern't in great condition and the clip that goes on the sensor itself was soaked in oil... anyone know if oil becomes conductive at high temps?

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i dont quite follow your story. could this be two seperate problems could the check light and engine not starting be due to a old factory immobiliser key? thats how they can present

when was the last time you changed your clutch?

The clutch hasn't been replaced, the thrust bearing is slowly dieing but its not clutch slippage, the clutch is still strong.

The engine not starting is confusing, but it has something to do with no fuel going through to the engine, ie the pump didn't switch on. Its never happened to me on start up before. (my immobiliser is 'active', it only switches on when the alarm is switched on but wont switch off till the alarm is reset) I think that the loss in power is related through the fact that maybe my elect tank fuel pump is cutting during hard running.

How would the main relay cut out from hard running?

but it doesn't sound like the pump is cutting from hard running, you said it struggled to run up a hill in fifth at 80. besides does the engine sound like its leaning out?

Quote:

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Originally Posted by SIKCVC

How would the main relay cut out from hard running?

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As i stated before - hard running = HEAT .....and the main relay and other electrical connections prematurely fail when exposed to excess heat.
Its a common problem for hodnas to experience overheating main relays.

Have a look and see for a start if ur main relay is in good condition.
Also fuel filter ?

its the engine knocking/misfiring when this loss of power happens??

The engine is running fine when the power drops, it just runs as though its a really high reving d15.

The fuel filter is brand new.
Airfilter has been cleaned

The thing about the main relay is that its inside the cabin... how would engine bay temps affect it??? although I do usually have my heater on full blast on my feet.

I will take it for a run tonight and see what happens.

Thanks for the help guys its much appriciated!

if the engines running fine why would it be a leanout? wouldn't you expect the engine to be knocking/misfiring? and if its cutting totally it would be like hitting the limiter?

if your clutch is starting to go it can seem fine when you are driving normally but when its hot its friction coefficient will go down and you will lose clutch grip causing some degree of slippage... which can happen if you've just had a hard run

how's your oil?

oils brand new motual.

Its just the thrust bearing thats going, the clutch itself seems fine, it still has plenty of grip... This is more of a bogging down feeling than clutch slipping.

Quote:

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Originally Posted by SIKCVC

The thing about the main relay is that its inside the cabin... how would engine bay temps affect it??? although I do usually have my heater on full blast on my feet.

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The engine is only inches away from the main relay - underneath the dash acts like a heat sink and abosrbs the heat thru the firewall etc . . . it is a common problem for some hondas for the main relay to be very faulty over time if excess heat comes into play ( you hoonign abit).

Take it out and find out. Best of luck

Ok, I replaced the relay with a much newer one... will give the car a push today and see how it goes!

Quote:

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Originally Posted by SIKCVC

Ok, I replaced the relay with a much newer one... will give the car a push today and see how it goes!

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:confused: :thumbsup:

Still to push it hard... Dont you worry I'll be back to complain about having a crappy car if it doesn't work :P

Just went for another heavey run (engine wise) and while it ran ok when reving hard, it lacked luster down low again. It also struggled/flat spots a bit when at WOT. Any ideas?

I have a constant bogging problem. it would drive fine but then lets say i am on 5th gear doing 60km @ 2000rpm it would run alright then bog then come back again. but when i rev it up a bit more it seems to go away. very intermittent. i'd say it would be the bearing in my dizzy. i've changed my dizzy cap + rotor button [btw my rotor button previously melted.. how i don't know and i was freakin out for a week.] now the car is alright but yeh after a hard run it seems to bog. check in the dizzy .. if u've got a lot of orange dust around that area it could be ur bearing. if let's say the bearing is worn .. particles of dust will slowly chip away from the bearing and then oxidises[rusts] and results in orange powder..
i'm probably gonna get a whole new dizzy..
btw i drive an 88 CRX d16a8..

check your timing?

too far advanced can lead to these symptoms

timing has been adjusted, tappets done too.

Its a subtle problem thats totally intermitant, this is whats weird. Think beyond obvious coz I've already spent a small fortune trying to solve it...

what type of air cleaner you got ???

a pod. Its pretty new done about 10km. it was the very first thing I changed when the problem started.

i dont think you have a problem.

what could be causing the flat spots after a hard run and the lack of power?

pseudo-psychological factors...?

happens to me...

kinda like the one when you slow down at the end of the freeway to 80km/h and you say "man this feels slow!!!"

maybe...???

i is also like when you hear people say " i ONLY use optimax - the others brands make my car feel slow..."

well - that feeling of 'slow' is a mental effect...

It could be true, since I spend all my time at 5K+ in the hill (in torque band) and then cruise in the low revs once i'm done, but still this feels more then that. I will try and set up a test so that I can know for sure. Also I will know after next friday at the off street drags. If my times increase I know something up.

have you change plugs? could be plugs acting up at higher temp. I had some plugs which acted up while cold and then were fine after the car warmed up. Try changing to a set of new plugs should cost less than $20 and it always help even if its not this problem.

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Originally Posted by tinkerbell

pseudo-psychological factors...?

happens to me...

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likewise :) Infact the mind can have a huge effect on the perception of a said cars performance (or lack of) Different noises etc. Problem is , cars my age ( 12+ years) the car actually is starting to fall apart so its not always in the mind :(

Quote:

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Originally Posted by SIKCVC

It could be true, since I spend all my time at 5K+ in the hill (in torque band) and then cruise in the low revs once i'm done, but still this feels more then that. I will try and set up a test so that I can know for sure. Also I will know after next friday at the off street drags. If my times increase I know something up.

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the problem is that the description you are giving is too random or inconsistent to be easily attributable to one thing.

but being able to say "it does it ONLY when blah blah blah" will help narrow it down...

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Originally Posted by tinkerbell

the problem is that the description you are giving is too random or inconsistent to be easily attributable to one thing.

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WHAT HE SAID hahahaa

And as for the different types of fuels, man it DOES make a difference, not so much in terms of seat-of-your-pants power, but in terms of the engine's smoothness and efficiency etc.

not sure if it's just cause I have JDM B16 that's tuned for 100 octane or not, but I always use BP Ultimate 98octane fuel as it's the highest octane fuel available in WA, however once I put in some Caltex Vortex 96 octane and the motor sounded more rattly, lett throttle response etc and the top end was no where near as smooth or efficient at making power. now it might have been technically making hte same HP, but it's delivery was no where near as nice..

well, in the eastern states we have a choice of 3 high 98 ocatane fuels.

and anyone who says their car feels slower using one 98 vs another 98 is making up stories...

96 vs 98 is different situation ;)

(sorry for OT)

Ok, the problem is related to flat spots between 2-3000rpm after a long drive(intermitent, may or may not happen) or hard running(will happen).

They're noticable as flat spots in 1st/2nd but in 3rd- it seems as though it hits the flat spots and bogs down and wont come out of it. There is no pinging then engine just seems laggy. The plugs have been replaced recently... a few times. New fuel filter, new airfilter, always 98ron. Engine isn't running rich or lean (as far as the plugs show).


Edit:
It doesn't seem engine bay temp related as it ran fine, temps were up at 40c then down to 20ish while driving all day and it ran fine for a while, then just started running crap again with the flat spots etc.

Nick

Any ideas guys? I'm taking it to tecknik tunning to be chucked on a dyno soon. Just want to try anything before I fork out $X00 to have it tested.

yeah i suggest taking it there too. that's where i've been getting my work.

dyno wont be same as road anyways.