aja

Hi guys, tried searching and found few almost similar threads but no answers. Well the case is my engine overheated about a month back. So got a new rebuild engine and had it installed. However the problem is now that after running a while and after the temp reach bout 85-93C the engine becomes rough and sluggish at low rpm (below 3000 or so, idle maintains at 1000rpm but engine sounds like a motorboat and vibrates) but once it reach higher rpm and boost comes in, all looks good. If I leave the car at idle for a few min it starts getting better as the temp reduces. Compression was tested and looks good on both rotors. Tried changing the coils and cables but results was the same. Than I removed the front injector plug (leaving the back) and the car died. So I tried doing the opposite and the car still moves at a lower idle. (This is only when the car is hot, when the engine is colder either injector can be pulled out without the engine dying). So thought might have some problems with the injector. So put in a set of new injectors and the problem is still there. Running out of ideas and hope someone can help out with this. Thanks

wiblergt

sorry man, i can't help you out there.

BUT

do you have any large pictures of your car? it is pretty freggin sweet!

aja

Hope this one comes out bigger. new to the forum still trying to figure things out

Kento

When is the last time you changed your plugs? Try putting in fresh ones.

aja

Got new sets of plugs on it too although one of it is blacker than the other

speeddemon7

im having similar issues with my car.Youre either not getting eniough fuel or youre not getting enough spark.
Faulty harness or perhaps ignition coils may be it as well.My cars exhast smeels like fuel as well and backfires.Im pretty sure that either my fuel or ignition system is slightly out of whack.

aja

Tried changing the harness and the ignition coils. Still the same when the car gets hot. Though its a fuel issue, but the microtech has been tune. Also its the same thing on the standard ecu also works fine until the temperature rises above 85C or so. As mention earlier there could be an issue with one of the injector seems not to supply enough fuel. Howeve this injectors has been change to a new one and the result is still the same

What could cause one of the injector to inject less fuel when the temperature rises?

speeddemon7

that my friend is a very strange problem indeed.maybe some of the pros would care to answer such a question.

aja

Waiting for the pros to answer the question My other alternative right now is to take out the engine and try a new one. Which is the last alternative that I want to try now! its gonna take a whole day to remove and install a new one

speeddemon7

I doubt the engine is whats causing your one injector to shut off while warm.its most likely a electrical problem or a semnsor of some kind.hmm.what about the fuel pump relay? or something similar that controls injectors.maybe its damaged and screwing with your injectors.

Snook

iTrader: (12)

why would you take out the engine and try a new one if you checked the compression and its high and even all around?

are you on the stock ecu? Do you have the idle speed controller hooked up? What have you used to adjust the idle?

TracyRX7

Try adding HKS twin power to your ignition setup. Its easy plug and play install basically. You may also want to check your fuel pump or add a FPR. It sounds like its misfiring due to lack of fuel/spark for some reason as it heats up, you may also want to check all of your grounds (ahh electrical fun!).

For wiring it could be the jacket of some wire is heating and expanding causing a short on the inside (could be it got crimped and the copper inside is split and doesn't touch now if jacket expands). I really hate electrical for @#$@# stuff like that which you can't see and you have to do stuff like...get the car hot and then run around with multimeter checking voltages

aja

I was on the stock ecu right after the rebuild. However the problem started than and the mechanic said that it could be the wiring systems to the engine as it was in a mess. Since I was considering going with a microtech sometime soon, I just decided to go ahead with it with a Microtech LTX12 complete with a new wire harness. Thought it would be alright after that. But guess that wasnt the problem . So as far as wiring and ecu, the problem is there after the rebuild with the old ecu and wiring also with microtech and the new wiring harness. This problem wasnt there before the rebuild and I was onthe stock ECU at that time. As far as fuel pump goes I got a twin bosch pump and a new sard fuel regulator on the car. About the only thing so far suggested here that I havnt tried yet is adding in a HKS twin power and getting the car hot and then run around with multimeter checking voltages . However as mention earlier coil and cable has been change but to no avail . Trying out another engine I guess is just a way of ruling out that the engine is not the problem as there are concerns that the housing surface might not be up 100%

speeddemon7

hmm.maybe this microtech device isnt working correctly.I would say try a new regular wire harness and run a apex power fc.it just might do the trick.
I think youre on t o something as far as the injectors not working once it gets hot.Stick with that.Because like you said.You unplugged it and the car didnt react differently but then when you unplugged the others the car died.That tells me that you arent getting enough fuel due to the injector not working.Keep working that angle.You will eventually figure it out.

htharv

I have a similar problem with my fd. And mine is completely stock. When the engine is warmed up and I've driven a while, if I stop the engine backfires at idle. People have also told me that when I accelerate at full throttle my exhaust smells like fuel. I did have problems with loss of power caused by leaking intake piping.

speeddemon7

just so you guys know im also having loss of power issues once the car is warmed up.but mine is more a loss of boost.I also have this weird rattleing that appeared right about the same time my loss of power.Who knows.When I have a chance ill have to check my downpipe and see whats up.

PandazRx-7

iTrader: (18)

The reason it's running rough and sluggish is because it's running super rich...happened to me twice before. The first time was when my Water Thermosensor was malfunctioning after the engine warmed up, the symptoms were exactly how you described it...and the second time was when my Air Thermosensor would malfunction when warmed up, but wasn't as bad, just a little rough. I would start with the Water Thermosensor. Are you getting codes?? I didn't...turned out my ECU was jacked up as well...hope that helps.

Btw, that's probably why your spark plug is black too.

jantore

I haev a similar problem, just rebuilt the engine. And just finished runing it in. At idle and to about 3000 rpm the exhaust sound is deep and "dark". But when i get boost and above 3000 rpm it's normal.

And somtime it stumbles at idle, going down to 7-800 rpm and gets a rough idle.
If i push the throtle it goes back to 1050 rpm.

And vacume is -17 psi at idle.

So what is wrong.

I have Haltech E6X and the HKS Twin Power.

aja

Air thermosensor was change during changing of the injectors... havnt tried the water thermosensor. no codes coming out

speeddemon7

man.Talk about a money pit.Im sorry youre going throiugh this AJA.
Youve damn near replaced everything on the car.Major bummer indeed.

aja

LOL... I hope I dont have to pay for all of it... since the workshop has got tons of parts lying around the mechanic decided to do a trial and error. So since most of the things switch gave the same results, means that the original items was still good and there was nothing wrong with them. Might have to pay for the workmanship though. Although workmanship is not that expansive over here If I do have to pay of all the parts than i might just have to burn the car and collect the insurance money . My money tree behind the house just died from the exhaust fumes from the fd and I dont have that much more left in my pocket

FD4S

Aja, what kind of mods have you got on your car? In Malaysian weather, it's often the case on a hot day that the FDs feel rather sluggish. Perhaps your air intake is getting hot due to insufficient intercooling or as was mentioned earlier .... your air intake temp sensor could be faulty or suffering from from heat soak. Are you running a single? Maybe next time you can try running the car and as soon as it feels sluggish, try feeling the intake manifold to see how hot it is.

aja

Yes, I am running single right now along with the necs mods. Greddy 3 row FMIC etc. Will try out the suggestion and see how it works out. The only thing that is bothering me is why now and not before!!! Thanks

aja

Well the engine swap has been done and up till now looks like the problem has been solve. Although havent fully tested it yet since now the aircond stop working and its in the aircond shop now geez talking bout a money pit and time spend