tervalentpage

Hey guys, I know i've seen tons of these threads about preludes having this heat issue, however i have done everything i have seen as common issues and that i could think of to solve my own problem, to no avail.

The car never has any issues when either it is cold or when its cool outside, I'd say below 70-75 i dont see any issues. She starts right up and is quick with no hesitation. Once she gets warmed up on a hot day however, its like someone sucks the life out of her. My motor only has about 65k on it so it definitely shouldnt be tired. It used to hesitate and bog a little bit when it got hot before i threw the chipped p28 in there, now she's always smooth but still lacks a lot of her power when its hot out and she's warmed up. on a good day she keeps up with nice running 350z's and ***** on mustang gt's and things like that, on her bad days she struggle to keep up with volkswagons and suvs. When i drive her for 20 mins or more, then park her for 10 mins and come back out and try to start it, it sometimes takes a few extra cranks to get started, a few times even requiring me to hit the accelerator(i know, sounds like a fuel issue). And 9 times out of ten, when i start her off a warm start, she cranks over, goes up to 2k rpms or whatever hondas hit, then when it drops back down and is supposed to settle 600-800rpms, she'll dip down to 100-200 rpms and almost stall for a few seconds before she re-calibrates and levels out. I am a business development manager and am on the road for work more the half of the week, I'm getting so fed up with dealing with this issues for 150-200 miles a day on a daily basis.

The car: 97 prelude base with a jdm h22a swap. Car only has a few boltons: full exhaust, headers back with a test pipe, aem cold air intake, and chipped p28 ecu. I have heatwrapped both my headers and my CAI to prevent as much heat from being drawn into the motor as possible, as well as built a fiberglass box above the air filter to really ensure the car is not sucking in any heat.

This car was originally a project, but i just blew the trans on my jeep so now i'm SOL and need to get her running pristine as my primary vehicle.
I originally checked the compression before i installed the motor and compression was spot on. In the past 6 months, I've done the timing belt, new water pump, new balancer retaining seal, valve adjustment, new valve cover gasket, new blox cam plug, new crank seal, new oil pan gasket, new oil cooler o-ring, new v-tec selenoid gasket, all new ngk plugs and wires, cap and rotor, new upstream and downstream o2's within the last year, new starter, all new vacuum lines on the intake manifold, new main relay, new knock sensor, new tps sensor which was calibrated dead on to .5 closed and 4.5 open, new battery terminals, cleaned my egr ports and egr valve, cleaned my throttle body out thoroughly, new map sensor, new iacv, new auxilary valve... and thats all i can think of off the top of my head for the time being.

With all of this being said and done, what can I even begin to narrow my issues down to? I've assumed it was a fuel issue, or lack there of, but I dont want to just go through and start replacing things for the hell of it, i dont have deep enough pockets for that. Everytime i turn the key on to acc, i hear the fuel pump click and prime with no hesitation, so where does this leave me?

I've pretty much done all that i could think of pertaining to solving this issue, and i'm at the end of my wit now. Any help from any of you other honda/prelude experts out there would be much appreciated. I plan on spending most of my weekend under the hood of my prelude, hopefully i can have her fixed up by the end of the weekend.

tervalentpage

By the way, I am new to the site but I have been working on cars for 10 years at this point. I've worked on mainly american muscle cars (several camaros, firebirds, and mustangs), as well as two or 3 VW's, a scion or two, several acuras, and several hondas, so I am in no way unfamiliar with vehicles. I did my 97 base h22 to jdm h22a swap myself, as well as others. Hell, just this week, I did a direct swap in a 06 rsx, k20z1 to k20z1 due to a blown rod/broken valve/scarred piston.

I know how these sites work and i'm expecting a few shots to the chin, just dont take me as an idiot. I do know my ****.

Thanks!

0Kaze-Speed

I would start by upgrading the radiator to a nice aluminum one, and installing a quality oil cooler as well.

tervalentpage

I've actually considered that since i know that heat is a vtec's biggest enemy, however i didnt think this would actually be able to cause a big enough issue to notice a substantial lack of power. By substantial lack of power, i mean it feels like my HP gets cut in half. If oil getting too hot was the issue, would i be able to tell by the oil pressure or any other indicator? Or would it be one of those shot in the dark kind of a deals?

tervalentpage

sorry, new to the whole forum thing. Didnt know if i needed to tag you in the response so i figured i'd just throw down another post. Correct me if im wrong in my ways.

jdm_rb20

Do you have any warm reading on the dash temp gauge? Oil light ever flicker on? And is there a CEL at any time you can remember (may only show up when it is having issues)?

The first thing that comes to mind is "timing"....bc that screws up your power. But first, I would check my spark plug wires when the intermittent power loss is making it run bad. While it is running bad, pull over to a safe area and pull only one spark plug wire at a time. If you pull a wire and the idle makes no change at all: bad wire.

My wifes car did that, and it turned out to be a bad spark plug wire. It would drive fine sometimes for days, but on a long drive or hot day, it ran like crap. Eventually got to where I could not pass a car on the highway.

Anyways, is it time to replace them as basic maintenance anyway? If you got the money just change them and hope?

If that doesn't fix anything, you should check your timing and sensors that affect time, especially temp-affected sensors: IAT, ECT, MAP, TPS (for operation and correct calibration).

tervalentpage

The dash temp never gets hot, the car has never even come close to overheating. Oil light has never once flickered.

I've had a CEL on in the past for egr and for evap, both of which were fixed and once i reset the light it never came back on again. They were on 100% of the time as well, and didn't only come on when the car was messin up so it doesnt appear to me that they would have anything to do with this issue.

I now am running a chipped p28 which ive installed since this issue has began and it has made it a little better but didnt solve my issue completely. Since i've installed my p28, i have not seen a cel either. All of my dash lights work because they come on when you first start your car for a second and then turn off like all cars do.

I had some red spark plug wires on there before which had a name on them i didn't recognize so i could only imagine where the guy before me got those wires, and i've replaced them with NGK wires, plugs, and a new cap and rotor at the same time, and it didnt solve anything for me. I will still check my wires next time it fudges up to see if it makes any difference anyway however, you never know, could be faulty wires or something.

Pretty much all of my external sensors are new (map, tps, iacv, auxillary, IABs have been bypassed, and even a new ecu altogether as mentioned before.)

I'll check my timing over the weekend again, but would timing being off affect the way the car drives in different temperatures?

1funryd

What color are you plugs like?

tervalentpage

my plugs that were in there for 9 months or so, when i pulled them out they had a decent amount of carbon on them and were a little black. They weren't white or burnt looking or anything, they seemed normal. My egr valve was dirty and o2 sensor was messin up for a bit so my car was running rich for a little while, so i expected the carbon. They weren't as bad as i had expected tho.

Rasmusm

Did you change your ICM in you distributor?

http://autorepair.about.com/library/faqs/bl446e.htm

If the ICM is bad car makes all kind of weird things Like hesitation, Tach gauge tripping lol. Mine did and it hesitated alot aswell

tervalentpage

I have not checked my ICM yet. I've heard thats a common issue as well. I heard that usually when the ICM starts messing up it'll actually choke the car out completely and make it stall, and sometimes prevent it from starting to begin with. I'm not so hopeful that this is my issue but i've gotta test everything.

jdm_rb20

Just more random thinking...We can proooobbably rule out the plugs, plug wires, and anything else that is new (as long as it got installed correctly...ie, no "swapped" harness plugs by mistake)..

I am gonna take my thinking back a step. I know you said that this problem existed before the p28 got installed....but did it get drastically worse when you installed the p28? If so, a tuner can use Hondata to try to pinpoint those conditions and troubleshoot it.

But that leads me to my next BIG question: Did you take your car to a tuner and have that p28 professionally tuned? Or are you running a "basemap"? Basemaps that come with the tuning software are merely a starting point for the tuner. A basemap may perform well enough to drive, but it is not tuned for performance and probably isn't tuned well enough to handle the conditions.

If you are running just a standard basemap, you start with a problem, mix in a basemap that isn't tuned, and end up with a substantial performance issue.

I will wait for your answers before I spend anymore time just rambling and thinking..lol I hope I am helping narrow it down some.

tervalentpage

I've checked all my connections on things installed numerous times, everything has been installed correctly so i know that is not an issue.

My car actually ran a lot worse before the p28 ecu. When i got my car, i did a full inspection on it and found out that the plastic nipple on the IAB box for the vacuum hose that runs to the intake manifold was broken off so i rerouted the hose back to an empty port on the intake manifold to make sure at least there was a positive pressure in the system. The p28 that is now in there has not been tuned yet professionally. I ordered my chipped and socketed p28 ecu from phearable.net and got the h22a basemap with all my existing mods tuned into it and my cars performance (when cool) increased pretty dramatically. I don't just mean that it got a bit quicker even tho it did, it completely rejuvenated the bottom end since the p28 doesnt run the IAB's so it bypassed that issue. It also helped my car a bit when the heat issue comes on and it starts messing up. Before, the computer wasnt able to re-calibrate all of the valves to deal with whatever issue is going on and it would actually hesitate and bog down a little bit. It doesnt hesitate or bog anymore, its completely smooth throughout the rpm range, it just feel like its at half power when its hot out.

I understand when you get a computer chipped and socketed for your specific car, that it is just a basemap tweaked to your cars mods and not an exact tune, but i'm not quite sure how that would affect the cars perfomance in different temperatures like it does. I just dont understand how it can drive like a bat out of hell when its cool out and like my old 92 accord sedan with 320k miles when its hot. Could this be a tuning issue?

jdm_rb20

Absolutely. Download a copy of hondata to your PC. Open it and open a basemap (any basemap). Then browse around the parameters section (if I remember) and look for "fuel compensation" (if I remember). Somewhere in there, you will see that you can tune your ECU to compensate for such conditions as: warming up (by watching ECT) and ...drumroll...lol....external air temperature (by watching the IAT). Yours may even be a combination of both of those "compensations": Hot air through the IAT and hotter coolant through the ECT may cause a double fuel-compensation (lean or rich...idk).

But that is something for a protuner to look at. I don't recommend doing it yourself. I played with "streettuning" my h22 basemap and now I am rebuilding because I ended up with low idle, causing low oil pressure at idle, and then a spun bearing

jdm_rb20

Also, I can't remember if there is a way to turn off CEL codes, but it seems vaguely familiar. I really hate telling you that you need a tune when you may potentially have a physical problem that needs attention BEFORE tuning....it's a catch-22. it is worth googling to see if hondata can "ignore CEL" or whatnot...

--TJ

tervalentpage

Thats an interesting thought about the tune then... If all else fails i'll probably do that last. I don't really have much else to check though so its probably not far away when i get my tune anyway.

I was planning on upgrading the intake manifold, fuel rail, fuel pressure regulator, fuel filter, and fuel pump in a month or two and wasnt planning on getting her tuned professionally until i had all of that finished. Since all my plugs wires and vacuum lines are solid, I'm going to check my ICM first thing tomorrow. Hopefully it'll at least help me diagnose if not resolve the issue.

And i'm not quite sure what you mean about ignoring my CEL. I dont have any CEL lights on. They don't ever come on when my car is messing up either. Other then when i first start my car and they turn on for a second when the key is in accessory, the CEL stays off 100% of the time.

Rasmusm

I would think you can Ohm out your ICM? To see if it works.
Let us know if it was the ICM.

jdm_rb20

If i remember correctly, you can instruct a chipped ECU (like your p28) to "ignore" Check Engine trouble codes....If so, the chipped ECU is not turning on the CEL under circumstances that the factory ECU would normally turn it on. I don't have hondata installed (because of a reformat) but you can probably google "p28 CEL" and find some input on whether it is capable of ignoring codes. If you need to narrow down the search results, just throw in random key words (like "ignore").

tervalentpage

Thats interesting, it seems like i just keep circling back to a potential computer issue from what it sounds like.

So this weekend, friday i changed the Main relay, and today i changed the ICM. I decided to just go ahead and swap them out without even testing. I know both are original parts from 97 and will become issues at some point, so i just changed them.

Still no changes... Car still drops to 100-200 rpms when i'm slowing down to a light and press in my clutch before it idles out where its supposed to be, as well as when i start it off of a warm start it drops down there and re-calibrates also. Still lacks power when its warm. I reset my computer after changing both sensors, and it didnt really do much for me. So... where does this leave me?

Once again, this is where i'm at:
Spark plugs are new, as well as cap, rotor, wires, ICM. There's no CEL. Main relay is new. Compression is fine. Cleaned my injectors, EGR valve, and egr ports(used the slide hammer to pull out the old plugs, scrubbed thoroughly, put seafoam back in the ports before i plugged them back up, then ran the car for a while afterwards). Just about all my fluids have been changed with genuine honda fluids, and all pressure systems requiring of it have been bled. Timing belt, water pump, balancer retaining seal, crank seal, and valve cover gasket have all been changed and adjusted. New IACV, auxillary valve, tps sensor, map sensor, p28 ecu, and o2 sensors.
... So why does she still not run right?

tervalentpage

So today at one point, i went to turn her on and she just cranked over 6-8 times before i tapped the gas and she finally kicked on. She cranks strong, shouldnt be an electrical issue. It has to be fuel related. Unfortunately i'm going to have to wait until friday for when i get paid again, but i'm thinking next i'm going to change the fuel filter to a high flow and the fuel pump itself to a 255lb pump. I have a strong hunch my issue lies somewhere along the lines of fuel. I was contemplating whether the fuel pressure regulater or something of that sorts could be causing my issue; technically its right behind/above the engine where its absorbing a lot of heat, and it doesnt have a sensor connecting to it which i would imagine would mean if it was messing it, it wouldnt throw a cel. I'm going to start with the filter and pump thought, see where that takes me.

Any suggestions on filters and pump? I was probably just going to go aem high flow filter and some standard oem brand 255lb pump.

Rasmusm

I have the walbro 255 its good. Always ran Honda filters though.

tervalentpage

I'm going to test my injectors tonight and see if any are different, then pick up the fuel filter and pump friday. Its a short week so i wont be driving much anyway, not to mention ive got a few parties to attend so its probably better i dont have my car in a condition where i'd want to bring it...

tervalentpage

well injectors are all in good shape. I guess we'll see what happens this weekend with the fuel pump and fuel filter. I ripped my car home tonight at about 3 am when it was like 60 degrees out, best she's run in a long time. Also coolest weather she's ran in in a few months... go figure right?

jdm_rb20

Remember when I said that an ecu compensates for intake air temperature? I will make no promises but theory states that temperature of intake air affections the combustion. That is why ECU's are tuned to compensate for different air temperatures.

Going back to your other comments (I have been busy for a couple days):

If your FPR (fuel pressure regulator) is going bad, even just intermittently, you will likely have CEL's because the o2 sensor will be reading rich/lean, depending on FPR allowing too much/too little gas through it. Instead of buying a new FPR just to rule it out, compare the prices of a FP gauge. It may be a wiser decision and give you something extra for about the same price.

About the Walbro, a walbro is a high flow pump that is designed to keep up with the demand of highflow injectors. If it is installed with a factory-set unadjustable FPR, your result will be rich AFR, which may also reduce performance if it is too rich for a good mixture. Just common theory, but upgrading the fuel pump is rarely needed unless you are putting out like 300+ hp and have highflow injectors and an adjustable FPR. Even with a demanding build (300+hp, highflow injectors), I think the fuel pressure is still usually tuned to the same fuel pressure that original setup had...not 100% about the fuel pressure of high-demand builds. But I am faily certain that the adjustable FPR is pretty much REQUIRED to lower the FP of the high-flow pump....the highflow pump is solely needed to provide that same fuel-pressure under high-demand situations (upgraded injectors are wide open at full throttle...the stock pump can't keep up with wide open upgraded injectors).

Basically, stick to the basics, and throw your money wisely. Seriously think about that fuel pressure gauge before you spend money on upgrading the fuel system.