CapedCadaver

iTrader: (8)

has anyone with a vg5 ever had the feeling that the car accelerates better at part throttle than full throttle? i noticed it today, that if I push it to 40% throttle at 55 in 5th, it gets to 60 faster than if i floor it in 5th. and it feels lethargic at WOT runs up to redline as well... it struggled hard to stay in front of my friend's 2.2L 5spd probe which is 30psi short on all cylinders (or at least that's what it was before we started it on the new HG so it might be back up to spec now) and has a bad ecu that cuts injector power after 4000rpm... and i was shifting at 5400 in 1st-3rd!!! friend also said he saw a little whitish smoke coming out... checking coolant and oil and compression tomorrow just as a precaution.

whattingh

Just a random thought. The tps maybe not well. why i think of it, is when throttle is pressed the tps ohm value go up. maybe there is something in bad tps that it gives wrong ohm value out to ecu.
No throttle is +-1kohm
partially 1-9kohm depending on how much throttle
Full throttle is +-9kohm
(FSM EF EC 145)

Pearl93VE

iTrader: (14)

This is why I always get on my car, to see if it's up to par, timing it, etc. If it ever doesn't respond the way I want it to in the times I allow it to run in, then something needs fixing and I search until I find it for the most part; unless you know what it is and you're waiting to fix it.

My car is always faster at full throttle...

CapedCadaver

iTrader: (8)

well i'm doing an engine swap in a couple months, using a good-ohming set of injectors and new o-rings, all new vac lines, belts, replacing the seals in the PS pump, etc. Hopefully that will eliminate all my engine-performance issues. I will test the tps anyways tho. I'm wondering if maybe my TB WOT stopper is too far out... allowing the throttle plates to open too far, and begin to close again (like 110 degrees of rotation which will behave like 70 degrees.) but the tps is a more likely culprit... to test the TB opening thing i'll just put a multimeter to the MAF and see what that comes back with (it'll limit to 2000, so it'll hold constant to let me adjust the throttle opening and see what i get)

edit: I also found and fixed a torn vac hose this morning (water solenoid valve) but it didn't really change anything. I heard a hissing sound from there last night so i was hoping that would change something.

ps pearl your sig is awesome... the layout, spec, watermarked name, and oh, the car

vernk

yea I have noticed that with a few cars I'v owned (even the one I bought brand new) just have to find how hard to push the gas for the best power, and how fast to keep pushing as the RPM go up.

my thoughts on it are that it might have something to do with that when you open it up to much for the RPMs that your at the ECU starts dumping more fuel (pre programed fuel maps) then what air the engine is sucking in therefore goes rich and you lose power, just a thought.

other then that make sure your butterfly isn't opening to far so that it's closing (sorry butterflyS) and is your VI working?

BenStoked

iTrader: (7)

to answer the original q', no it aint normal on a vg5. of course, mine accels the same from 75-100% throttle, but my engine is being funny. hope to get a rebuild done in the near future.

1992maximase30

vg-5spd?
may sound stupid but if your in 5th gear and you floor it well yea it's dumping fule but not suckin in the same amount of air because it's slowly revvin well not slowly revvin...

or it could be your variable induction system not workin...

and pearl i thought i was the only one to get on my car

3g94MaxGXE

I used to think the same thing, back before I had mastered the auto. My problem was that it downshifting took too long and it shifted into 2nd too early for my tastes....though lately I'm beginning to think it's adjusted to my driving style and shifts too late for economy driving. WOT is the way to go though no doubt about it.

CapedCadaver

iTrader: (8)

VI worked last time i checked, but i'll check again. coolant is green still and oil is brown still so no mixing there. didn't get to check compression tho. that smoke still worried me though.... i saw it out the rear and my friend was following and he saw it too. he said it was white, not blue, not gray, not black. so i dunno what that's all about. but as long as the HG isn't blown i'll just let it be until i yank the motor at the end of summer and let everything sort itself out when the 'new' motor goes in.

but with the thing about being in 5th, that's understandable... but it doesn't feel like it's got much zip when shifting at 3k or 4k or 5k either.

JC93SE

Caped:

First thought when I read your first post was a stopped up converter. How many miles? The white smoke makes me think coolant- head gasket or a cracked something-or-other. Any "mysterious" loss of coolant- resevoir slowly going down over time? Any smoke makes me wonder if the converter hasn't gotten contaminated and clogged.

I also thought about weak spark or bad plugs, but you'd likely notice the miss- so probably not.

I could be wrong- hard to tell from 20 min away. :-)

CapedCadaver

iTrader: (8)

i haven't noticed the coolant level dropping any, so i have no idea why it would have made any white smoke. i'm about to go outside and check compression just to see. 167k on the cat. i'll check plugs as i go. i've had a slight miss in one cylinder for quite some time now... so that's been somewhat of a constant thing, and i didn't notice the smoke and weakness until thursday.

CapedCadaver

iTrader: (8)

compression results:
1) 180psi
2) 178
3) 164 (lifter perhaps?)
4) 177
5) 178
6) 179

took all measurements 2 or 3 times to ensure consistency and accuracy. either way, these results to not explain any percievable power loss. the real issue is most likely just that when it senses WOT and goes to openloop, my fuel delivery is making it go richer than it needs to, and therefore robbing it of power.

1992maximase30

which is pretty common,imo, becuase mines do the same thing.
some people misread smoke signals.
john thought my car was burnin oil but she's not.
she's running rich.

you would noticed your car burnin coolant.

JC93SE

OK. What is causing the miss??

CapedCadaver

iTrader: (8)

god knows dude... i highly doubt that 164psi is low enough to make a miss big enough to feel through the shifter handle. it's probably an injector, a bad wire, a bad plug, or whatever. all the plugs looked basically the same though. it's a partial miss, so the balance-load test won't even work, because ALL cylinders will cause the engine to run worse when their spark plug is unplugged... thus almost impossible to identify which cylinder is being a meanie.

JC93SE

I know it's my fault, but we're chasing two problems here. My point was that you have another problem that you haven't chased down. (I know... it aint easy) Multiple problems make multiple headaches.

Throttle Bog: You have some things that you mentioned that you haven't checked yet: TPS, MAF. I'd say it's time to check how many vacuum hoses are split at the connections too. Make sure the throttle cable runs where it's supposed to in the engine bay. Won't hurt to check the opening of the TB... doubt is an issue... worth checking though is that you are actually getting WOT- slack in the cable if you haven't already tightened it up. If you weren't fogging the road it WOT... it's a minor issue for the moment.

I still think it's worth checking the cat... that would do it too: more gasses trying to get through than can, and backing up and cylinders not getting cleared. I bought an exhaust pressure testing set a few years back that has a 15lb gauge, length of hose, a drill bit, an NPT tap, a thing to screw into the tapped hole you made that the hose connects to, and some short stainless bolts/plugs to plug the holes when you're done. The company I got mine from no longer has a website. Fun to play with... seeing what the pressures are at different points in the exhaust. in your case... what the pressure is before the cat, and after if possible. There are kits available that screw in to the O2 hole. You could make something with some ingenuity.

The miss: are your cap/rotor/wires reasonably fresh? Tight? Not too many miles on the plugs? (ahhh, if I and everyone all had occilliscopes and knew how to use them) I actually had a defective plug not long ago in my VG. Ohm tested the injectors? Cleaned the contacts on the ones you can get to? Is it missing at idle, or do you feel it while driving? Could be an injector, could be an o-ring... could be none of the above.

Hope I helped confuse you.

JC93SE

Of course, it won't matter in a couple of months what the problem is.

Grab a couple/three extra injectors and send them all (8 or 9 of them) out to be cleaned/flow tested/matched for the new engine. I going to check soon if there's a decent outfit in our area (Triangle NC) that does this so that I don't have to send mine cross country.

Chris Gregg

iTrader: (59)

Caped: Cylinder 3 is definitely out of spec. I would argue that this condition is enough to cause a miss you would feel. Minimum copmression is 142 psi and the maximum difference between cylinders should be 14 psi. I doubt it is a lifter. The FSM suggests putting oil into the low cylinder to see if compression increases...if so, then it's rings. Otherwise, it suggests looking at the valve seals.

JC93SE

I know this is a stretch right now, but the miss, lower compression, and funky throttle power loss could all be related. Imagine over time a leaky injector washing down the cylinder wall thus wearing the rings, at the same time it's contaminating the converter. It's a stretch... but possible.

I'm not sure the lower compression at that level would be noticed as a miss... though it is about a 7.5% difference between the it and the next lowest reading. Bit I said "I'm not sure". Also, "miss" hasn't really been defined yet.

I'll shut up now.

CapedCadaver

iTrader: (8)

MAF seems OK.. i'll recalibrate the TPS today. throttle cable is slack-free and going to the proper location. all exhaust components from the head to the bpipe are getting replaced unless the manifolds are still true. cat is being replaced b/c of how rusty it is and the complication of trying to refurbish the flanges to make it useable again.

cap rotor plugs are about a year old (15k mi) and the wires are nissan OEM and i don't know how old they are. once again an item that will be held off on until the "new" motor is put in. the "miss" is not very feelable at idle, but under any load you can feel it tapping against the shifter and hear it a little bit too. in conjunction with the broken motor and trans mounts i have, it is enough of a miss to cause a condition that emulates clutch chatter but in reality is just a bouncy engine. i can take a vid of that.

JC93SE

... and the injectors?

CapedCadaver

iTrader: (8)

i have a set to put in that all ohm'd in at 12.5 except 1 was 12.4. these injectors are 'ok' but remember this motor's getting plucked and put in another maxima but the one i'm keeping is getting a better motor setup. so all i care about is fixing stuff that lies outside the realm of an engine assembly... but the injectors, vacuum stuff, tb, iacv, and all that jazz are swapping in from the other motor.

vernk

if it's missing under load only it's more then likely spark related and are you still on the auto ECU, that might add to the WOT issue

ajcool2

iTrader: (43)

Funny title lol.

CapedCadaver

iTrader: (8)

true... maybe i should swap over to the manual ecu just for s&g... it's collecting dust as it is so why not, right?

daftinnovations

ecu don't really need anything higher then 4.0 volts at WOT from tps. check it at wot . the white wire in middle on tps.