Thread: I don't know what to check next....

I've been having a surging/lack of power issue for about two months now. It has been intermittent throughout these two months which is why i believe it's taken me so long to diagnose. It does not do it during any specific rpm range or in any specific gear. The two conditions it does do it under is generally when i'm at a light and try to go it will bog and not accelerate. I have to let off the gas and let it chill for a bit and then it will be okay again. The other time it does it is when i'm cruising and i try to accelerate it will feel like there is no power and if i give it more gas i will loose power and it will on some occasions buck like i don't know how to drive a stick.


Car has 178k on the clock.


Things replaced:
Fuel pump, Fuel Filter, Injectors, Spark Plugs, Spark plug wires(Taylors), Battery(odyssey)

Mods:
Koyo radiator and bumped timing 17* (if you consider this a mod but just to clear things up), Home bored out throttle body(gasket match), did the same thing with the intake plenum to match Throttle body), EGR removal. Thats all that i can think of right now.

Things done to try to resolve issue:
1. Cleaned all grounds
2. Checked TPS sensor it was right on.
3. Re-grounded MAF

Things i don't know how to check that i suspect might be the issue:
1. ECU - maybe gone bad??
2. Distributor - as far as i know it's factory original so it might be on it's way out.
3. Ignition chip - maybe bad or dieing?
4. Coil - maybe be bad or dieing?
5. Lack of fuel - don't how to check since it is intermittent.
6. Not enough spark due to newer cables - maybe the Taylor's are drawing too much power??(silly i know but it never hurts to ask)

Any help would be appreciated, i have been trying to solve this and can't i've tried to look through both forums to see if someone had similar problems but there problems where usually solved with one of the things i've already done.

For sure replace your cap and rotor if they have 178K on them. No doubt that they suck.

Are you sure the timing is still right on?

Did it run normal after those mods and just started doing that recently?

You can get a cheap gauge and put it inline to check your fuel pressure.

seafoam...

Sorry forgot to add cap and rotor have also been replaced. they are less than 2 months old. Yea i've checked timing several times, i've even taken off the valve cover and checked my cam timing to see if that was off but it was dead on. The mods were done to replace worn out OEM stuff. Koyo replaced old ass radiator that was leaking. Battery replaced one that had and unknown amount of miles. Home brew bore out has been on there for a while and this just started happening. same thing with the egr removal.

Problem has only been recent within that past two months. some of the stuff i replaced was while i was trying to trouble shoot this problem and also because it has a lot of miles so they need replacing.

I had a spare plenum and runners that i cleaned the Sh*t out of, those are the one i used to bore out and are in there now so sea foam wouldn't do much if anything. and i did the sea foam thing into the intake when i first got the car, which was a little over a year ago. i have also poured it into my gas about once every three or four months.

if this is a b13 you need to reground the maf if you havent already, check all grounds that go to the intake manifold and make sure they are intact and tight. If you have done these things and its still doing it, check your tps voltage and try to set it if its off. supposed to be .45V with closed throttle. Those are the two main things that can cause your symptoms other than the stuff you have already done, my guess is being that its intermitent, is the MAF ground is going bad so it needs to be reground. Your ecu is getting intermittent voltage loss from the maf and it would cause it to do exactly what your describing. Same goes with the TPS, if set incorrectly it will bog like crazy and hesitate badly.

Forgot to say this is an NX 2000. I've re-grounded the Maf already and checked the tps. i'll do it again tomorrow just to make sure it's dead on never hurts to recheck. i'll solder the connections rather than the butt connectors that are currently on there now. maybe they are not tight enough. .45v closed and 4 at wot if i remember correctly. i'll look it up before i check it again it's kinda dark out now so can't really do it now.

it could be a distributor problem, try setting your tps farther ahead out of spec, like a little over halfway through the adjustment and see if it goes away as far as the hesitation. if it does you could have a bad tps sensor. There are many little quirks you can do to try and work this problem out.

I'll try swapping out with another TPS i have laying around. that thing is just such a pain in the ass to work with. there is not much space there. Yea i've been told the distributor might be going out, it's on my list of things to replace soon. although i can't decide to either start getting an MSD set-up or just keep it stock. i do plan on going boost once i have all the small things figured out and a new motor 178 is not something i would feel confident boosting. Yes i know people have done it before and it worked fine i just would rather have a fresher engine, if not a built one.


::EDIT:: Thanks for all the suggestions. Gotta love this community.

if you need a distributor i have one, gimme $50 shipped for it and i will send it to you, but before i try to sell you something, you might try taking off the cap and rotor, then the metal dust plate and check the light disk with all the tiny slots and make sure the disk is spotless and clean, its possible the seal on your distiributor shaft could have went out and caused a tiny bit of oil to get in there. Very rare but seen it happen, if its dirty take some quick dry brake cleaner and spray it down really really good, then let it dry to make sure all the brake cleaner is out or spray it out with compressed air at a good distance to not damage or bend the disk, Try this after trying the TPS trick.

Hell yea, i'll deff try that. i have all of tomorrow afternoon off so i will have plenty of time to try things out. Thanks again