rhino37

Hey everybody my rex has one wierd problem. To give a little background:
-My last engine died, so i put in a j-spec

-When I drove the car home it would not rev over 3500 rpms in any gear unless I barely pushed the gas

-I decided that it needed new plugs, so i cahnged them. no help

-tried adjusting the tps-no help

-put on another spare tps-no help

I drove the car again. in 1st gear it revs perfectly to redline. in gears 2nd and up if i floor it it will only rev to 2800rpm then bog until 3900 then it will rev all the way to redline, but with a lot of backfiring and popping (not detonation). If i barely and i mean barely touch the gas, maybe an eigth or less throttle, it will rev cleanly to redline (no backfire or bog). What the hell could cause this?

My mods are as follows:
87 T2 with j-spec (all us manifolds and such put on j-spec), downpipe, test pipe, hks cat-back, hks powerflow, evc III, s-afc, bonez clutch

Thanks,

Ryan

Erik

wow, this is crazy...ever since i got my TII 2 weeks ago, everyone seems to be having hesitation problems (including me!!!) i also have a weird bogging hesitation around that RPM range. on my 15 hour trip of driving it home it was much like you described. once i got past the hesitation point it would pull till redline...but in the lower RPM's it would buck and hesitate...so severe in 1st gear that the rear tires would actually chirp! it would stop so suddenly...

i also have been trying to trouble shoot it. i tested the TPS and it appeared wayyy off...plus the adjustment screw wouldn't move and neither would the nut on the end of it. so this week i'll be putting in a newer 91 jspec TPS. other than that the only thing i can think of is a vacuum leak somewhere or a desperate need of a fuel filter. but i also have a funny idle now until the car is warmed up...possible signifying a shitty TPS.

the other day my friend with a turbo integra suggested that maybe the wastegate isn't opening properly...but i dunno...its gotta be something electrical

good luck man...lemme know if you solve anything...i just hope i can fix mine as well...or else i'll be depressed for a while..............

rhino37

Hey i have the same problem with idleing too. It won't idle until warm. It just starts then dies, unless i keep it revved up. Just so i make sure about adjusting the tps. The adjustment screw is to the left of the tps correct. It adjusts the throttle's resting point, right?

-Ryan

forgot to add that i have 850cc secondaries

The Ace

Dont really know what could be wrong, because I have never heard of something like this. But if it happens only under heavy throttle, then something must be wrong with the fuel supply. Secondaries come online at that specific rpm range, and if you have any kind of vacuum leak or filter problems, this might be causing the hesitation.

HuggyBear

"but i dunno...its gotta be something electrical "


this very well may be the problem.

the hesitation may be due to bad grounding, causing the secondary injectors to hesitate or bog around the 3800 rpm range. this is a known problem. youll have to set another ground under the hood. its easy so dont worry. just search the net under 3800 rpm hesitation.

Erik

do you haev a site tutorial about grounding? i have no idea how to do that. also, my car doesn't just hesitation around 3K...it won't GET OVER 3K!!! hehe...it just bogs and farts

scse12977

what you guys got is called the 3700 stall

normaly this only happens on the NA. it happens aroud this rpm because this is when the secondary injectors come on and the primary shut off.

heres what u need to do.

pull up the carpet on the passender side
remove the metal plate
look at the ECU
make sure all the connections are good

one of the black wires on the smaller clips (dont know which one anymmore) is prolly loose. this controls the secondary injectors ground.

thres a site somewhere with better instructions. ill see if i can find it.

I just replaced my ECU. and the problem dissapeared. But i also had a SE model that got a ECU out of a GTU.

hehe looks slow goes fast!

good luck

Erik

yeah, that makes sense...but i don't see how that would control my rough idle till warmup. also, i went to start it the other day and it started, then died after about 15 seconds...

HuggyBear

primary injectors cut out? i was under the impression that primaries run at 60% capacity or so till the secondaries kick in, then its a 40/40% split between the 2. can anyone clear this up?

it wouldnt make sense for the primaries to cut out totally since if there was only 2 injectors running at any one time all you would need is 2 injectors, not 4.

Icemark

I'm thinking grounds as well, the stock ground on the motor are very weak... at the very least I would be looking at upgrading the motor and battery grounds to an additional 8 awg wire 9though I must admit that I am a little puzzelled by the fact that rhino37's car will run fine in first gear... that screams ECU mis-adjustment or 02 sensor failure too me.

jaysT2

hey guys... my T2 will drive for like 5 miles like a champ and then it'll buck and kick like a lil bitch...all around in the 2500-3000rpm... i'll be cruising along and it'll just start to die and buck... any ideas??

thanks

rhino37

Aight update on problem:

Re-adjusted tps, and checked to see if it was any good

Changed ground, add from battery to ps pump bracket

Reconnected connector on air bypass solenoid

Adjusted timing--if i moved the locknut towards the firewall it would help with hesitation, but start smoking like mad

Played with s-afc...to get car to idle bottom rpm band must be on full rich...car runs best with next two rpm bands also on full rich...the last two are set slightly rich

Water thermo sensor was disconnected...reconnected it


Nothing helps...still hesitates at full throttle betwen 2400 and 3900 rpm...then it backfires all the way up to redline. If on light throttle it will run all the way to redline with no problem.

Also it's now running a little on the warm side

Another thing-when i changed the timing it would idle 100% better, much higher and i could lower the s-afc settings to a little on the lean side

-Ryan

Icemark

No replace the battery ground (At least a 4awg wire), replace or add an additional 8awg wire from engine to the fire wall. In some cases I will also run a new 10 awg ground wire from the body of the ECU to the passengers kick panel spot.

I also would be checking my spark plug cables... if the are still stock and have over 60K miles, they need replacing as well.

rhino37

bump

rhino37

I finally fixed the problem...I'm not sure what exactly it was, but here are the things that I fixed

-TPS was out of adjustment (used single DMM method) was at 1.9K now at 1.003K

-ECU ground was not connected

-added ground from bellhousing to chassis

-added 4awg ground from battery to intercooler

-vaccum lines on back of TB were disconnected!

-while removing upper intake to fix vacuum lines I notice that one of my injectors was melted, so I put in a j-spec.

Now the problem is totally gone except for when I first start in the morning it won't idle till it warms up a bit.

-Ryan

Erik

rhino37...check your pm's

Josepi

Erik, just wondering how your TII is; ever try any of this stuff? I took the IC off mine and played with the following (moved around)

Throttle cable
Engine harness ground
Battery Neg cable
TPS
Throttle cable

and the weird hesitation I had went away for a while. If it stays away or comes back eventually I am going to narrow it down...

PraxRX7

I only have hesitation in 3rd gear at 3000 RPM working up from 2500, and it only happens once in a while. It is probably just something to do with the grounding of my secondary injectors (as well as probably my old clutch which is being replaced right now)

The Ace

this was disconnected, the other was melted, the third was missing...shiiitttt man, I wonder how your Rex worked at all, let alone idle properly or maintain power !!!

HAILERS

Rhino 37......The part about not idling until warm just go to the fsm chapter 4B on adjusting the fast idle. Its possible its out of adjustment and the fast idle cam on the water thermo wax is'nt adjusted right. In fact its probable. Either that or the water is'nt flowing thru the throttle body for some unknown reason. See page 4B-62 of the fsm at http://www.iluvmyrx7.com Oh yes, for what its worth. On the back of the throttle body, of those four nipples, only the bottom one is pulling a vacuum. The top three do not pull vacuum. They lead to a path thru the throttle body to a 1/4 inch hole in front of the throttle plates, therefore no vacuum being pulled by the top three nipples. The largest of the three nipples supplies filtered air to the oil injectors. The bottom on that pulls vacuum should be going to the water thermo valve and then to the double throttle diaphram for use in cold weather.