cant rev past 2k rpm when driving

[shaeff]

ok, here's the scoop. i'm in a hurry right now, so i'll be able to reply later tonight.

when parked, i can rev it up to about 3500 rpm if i keep letting off and hitting the throttle again. it coughs and sputters alot.

no codes, and i tried the electronics from my old AFM. no change.

fuel pressure at 40psi with vaccuum off.

only thing different internally is 1mm OS valves.

base timing is good, as is ignition timing.

i have the lex/550 combo, walbro, j pipe removed, and an AFPR. when driving i cannot rev past 2k rpm. i'm running rich, so i'll lower the fuel pressure a bit, and the plugs and wires are brand new. MSD 8mm wires and autolite 3923's gapped to .29

any recommendations? vaccuum is at 20

-shaeff

 

[thesupraman]

Sounds like you are hitting fuel cut so I would say AFM for sure, but you already ruled that out. Same problem happened to my buddy with an MR2 and it turned out to be a faulty TPS.

 

[GrimJack]

When this happened to me, it was a dead AFM the first time, and a bloody big IC pipe leak the second time.

 

[shaeff]

hmm. i checked the TPS before i put the TB back on. it checked out perfect. i didnt see/hear/feel any IC leaks, but i'll surely check. i'm going to re-check the base timing too, as i've heard that if it's like a tooth off it can cause the same thing. keep 'em comin'!

-shaeff

 

[shaeff]

alright. let's try this again. i have no boost leaks, i have new RC 550's and the lex AFM, (tried both sets of electronics, same results) base timing is good, ign timing is 10* BTDC, ive got a walbro 255, AFPR with pulsation dampner removal line, and at a standstill, in neutral, i cannot get the car to rev past about 4k rpm, (really trying, feathering on and off)

when driving, it doesnt want to go past 2k rpm.

i have no codes. i pulled the plugs, and cylanders 3 and 4 look to be much more clean than the others. (all others are dark from running rich)

is it possible for the motor to run if it's 360* out of time? say if it was TDC on the exhaust stroke, instead of the ignition stroke? would the motor even run?

i'll try bench testing my AFM tomorrow. i'd really like to get this going. its not drivable like this, and once this issue is sorted out i'll be able to boost again after 6 months of having the motor on my garage floor!

any more suggestions, anybody?

would switched injector wires do it? i'll check those tomorrow too, i suppose

-shaeff

 

[gixxer750]

360 degrees out of time would be in time. The bottom end doesn't know if its on the intake or exhaust stroke, nor does it care. I say try unplugging your TPS and drive it. if nothing else you can just plug it back in. That's where my money is.

 

[shaeff]

(oops, i'm an idiot. brain fart. everyone's allowed one/week. )

i already tried unplugging the TPS. its definately not that. it checks out fine, and i dont have a code for it. i've had TPS problems on my old motor, so i know what they feel/act like.

i think the injector wiring is messed up. i looked at the TSRM on the injector wiring, what does W-L mean? i assume that W-R is white/red stripe, W is white, R is red, Y is yellow, B is black... but what does W-L mean? perhaps my problem lies in the injector wiring...

... i checked timing AGAIN, and its fine.

keep 'em comin guys. thanks!

-shaeff

 

[lagged]

how does it idle?

 

[shaeff]

it's got a slight miss at idle, that gets progressively worse higher in the RPM range. i cannot get it to rev high at all.

i just checked my injector wires against a post i found on SF, and i have them wired perfectly. i'm at a loss here...

-shaeff

 

[shaeff]

ok, i listened to the injectors, using a mechanic's stethoscope. they're all making noise, some are clicking, some sound as if they're popping, and one of them sounds like its knocking. like knocking on a door. could this be the problem? i've never listened to injectors before, but i'd assume that they should sound the same.

like i said, some are distinctively clicking, some are popping. and one sounds as if it's making more of a knocking sound.

if i increase base fuel pressure to 50psi the motor gets noticably more responsive. (but 50psi is way too much fuel pressure!) however, the miss doesnt go away, and between 2.5k rpm and 3k rpm, it just sputters, and wont go higher.

come on fellas, i really wanna drive this sucker! it's been too long!

i checked the coilpacks, they test perfectly within the TSRM specs. as does the ignitor. i took off my MSD 8mm wires, and replaced them with my old wires (which were working fine before removal, 6 months ago) and there's still no change.

i'm going to check the injector grounds under the intake manifold. any more suggestions would be great. thank you.

-shaeff

 

[IHI-RHC7]

I'll bet your cam(s) is/ are a tooth off. you can still have perfect ignition timing with the shaft itself off a tooth.

 

[shaeff]

well, considering i got a new timing belt just the other day, i actually decided i'd replace it since mine had a little oil on it. when i pulled everything apart, base timing was absolutely dead on. so it couldnt be that.

now, here's an update on the situation. (stupid dealership gave me the wrong belt, grrr... i'll get the right one probably by tuesday or wednesday)

-UPDATE- i think the RC injectors i got really aren't RC's. i called RC engineering today, and they told me that every one of their injectors P/N's start with a "P" or "S". mine dont. so whoever that kid was that sold them to me before the hack, screwed me. oh well. i got a hell of a deal on them so i dont really care. so now i'm on the lookout for new injectors, as i have NO idea what these ones are. i really believe the injectors are the problem.

i've eliminated virtually everything else! ?! no codes, AFM bench tested perfectly, TPS is fine, ISC is fine. what else could it be?

-shaeff

 

[suprabad]

Were your old injectors working properly? Do you still have them?
If so, slap them on just to test you theory. It would be a shame to buy new injectors only to find out that's not the problem. Good luck!

 

[shaeff]

well, i would, except i had to cut off the old injector clips to put on new ones for the new injectors. my old ones were working just fine. maybe i'll make an extension harness or something...

-shaeff

 

[GrimJack]

Pull a couple injectors and take them down to a shop, have them tested for flow, and then you'll know what they are.

 

[shaeff]

that's probably what i'll end up doing. my only concern is that they aren't even right for my car. they look just like the RC's, but the p/n is way off. thanks for the suggestions

-shaeff

 

[shaeff]

TO THOSE OF YOU WITH AN AFPR!!!

when you rev the motor, does your fuel pressure drop? the more i rev the motor, the more my fuel pressure drops, i thought this was because you're injecting more fuel into the motor, but it should (makes sense) that the FP should stay constant, right? so my problem might not be my injectors, but instead running out of fuel? (read: low fuel pressure at 3k rpm?) would this do it?

i'm using the stock line for the fuel pressure up VSV. (and still using the VSV) if that sucker is fried, would that cause my problems? i'm at a loss here. i was thinking it was my injectors, but now after reading a post on SF, i'm thinking its a fuel pressure issue...

-shaeff

 

[stevevangst]

TO THOSE OF YOU WITH AN AFPR!!!

when you rev the motor, does your fuel pressure drop? the more i rev the motor, the more my fuel pressure drops, i thought this was because you're injecting more fuel into the motor, but it should (makes sense) that the FP should stay constant, right? so my problem might not be my injectors, but instead running out of fuel? (read: low fuel pressure at 3k rpm?) would this do it?

i'm using the stock line for the fuel pressure up VSV. (and still using the VSV) if that sucker is fried, would that cause my problems? i'm at a loss here. i was thinking it was my injectors, but now after reading a post on SF, i'm thinking its a fuel pressure issue...

-shaeff

Shaeff, haha it seems like were both helping each other huh? lol well anyways yes the fuel pressure is SUPPOSE TO RAISE, not drop. if it drops then it might be your pump or you losing fuel pressure, what about this, once I had somekind of a problem and it was my pump, the way I found out was when I shut of the car it fp drops from whatever I set it to very fast to 0, I mean not fast but enough for me to see the gauge slowly go down, on my other car there's no way you can see the gauge drop when the car is shut off, all you can see is it just keeps going lower, but can't tell as it bearly moves and slowly does it too. does any of this make since? WEll anyways are you 100% sure you don't have ic leak, better do a leak test before you say no I don't. I worked on a supra that had the same problem you did, and guess what, lower ic pipe where you can't feel or hear was poped. that will cause you dang afm to read all crazy and not working right,

PAY CLOSE ATTENTION.

One way you can check is by taking your afm, and routing it right onto your tb, run it as if it was a non turbo, yes that's right non turbo, hook your ic pipes from the 3000pipe right onto your afm, make sure you don't have a leak between your afm and 3000pipe, i'm sure this well change something, try it and let me know bro.

GOOD LUCK TO YOU......

I HATE DUMB SUPIT PROBLEMS!!!!!! LOL :nono:

 

[shaeff]

alrighty, i'll give it a shot when i get my timing belt back in. my fuel pump is a brand new walbro 255, and the fuel pressure gauge moves incredibly slow, i know that, but i havent actually monitored it to see if it visibly loses pressure after i shut the engine down.

here's a FACT: when i rev the motor, my fuel pressure DROPS. is this because i'm using the stock VSV? maybe the VSV is fried?

the pressure still drops when i have the vacuum line detached and pinched off, (but i would assume that's normal because there's no vacuum index? damn i wish i had a timing belt!

-shaeff

 

[stevevangst]

alrighty, i'll give it a shot when i get my timing belt back in. my fuel pump is a brand new walbro 255, and the fuel pressure gauge moves incredibly slow, i know that, but i havent actually monitored it to see if it visibly loses pressure after i shut the engine down.

here's a FACT: when i rev the motor, my fuel pressure DROPS. is this because i'm using the stock VSV? maybe the VSV is fried?

the pressure still drops when i have the vacuum line detached and pinched off, (but i would assume that's normal because there's no vacuum index? damn i wish i had a timing belt!

-shaeff

in no way is the pressure suppose to drop when you rev it or when the vac line is off the fpr, unless you rev and then let off it is suppose to come back to normal because ofcouse the vac pulls it back, i'm sure you know that tho....

timing belt, hehe I have plenty....... :biglaugh:

god dang me and you haven dumb shitty problems.