(been a mechanic since 1984....seen it all and done it all but still don't know it all.....so i need some help)
i got a kids car that likes to drive in the upper rpm's....not
pegging them but more than normal....it is a stickshift,4cyl
vtec with 250K on it....i must say it drives beautifully
when you drive it like a grandma....but when it gets to
opperating temp it will absolutelyfall on its face when you
ask for more than aprox 2,200 rpms (under moderate
acceleration)...i have had it fall at 1,800 but more around
2,200-2,600....when it happens,you can floor the gas and
nothing changes....it doesn't caugh,backfire,catch
up,nothing...just as if you turned the key off....i have NO
ck eng lite...just a symptom...no the oil level is not low
(vtec)....i tried new from dealer a vtec solenoid and
distributor....also tried a new electrical portion of the
ignition switch....fuel pressure is 44lbs hot running and 48
hot with vacuum hose disconnected from regulator and plugged
(ran car with fuel pressure guage on it and it didn't
drop)...i assure you the cat conv is not clogged....also
tried a map/baro sensor (nothing has helped)...what am i
missing?...starts fine,idles fine.......i will say
this...THE CAR DRIVES FLAWLESS COLD......when first started
in the morning all the way to the shop i can't even get it
to laydown on me....when it does act up it is a performance
issue across the board,NOT AN IDIVIDUAL CYLINDER
ISSUE....when it is doing it,if you back off the throttle it
will pick up and go...till you get further in the
throttle....i'm going to scan the data for issues but not
sure what to look for...H E L P....please....steve elliottalso tried removing injector filter/screens and a new rotor button....could it be a bad pcm/rev limiter?....also checked timing belt timing.....dead on....

Steve Elliott
Owner/Technician
Steve's Shop Inc.
Louisville, Kentucky, USA

 

things been beat to hell but when cold youre in open loop/full rich.
closed loop everything changes, sensors come online.
on your scan tool go into datastream and look at the fuel trim.
beat up lil VTAC isnt getting any gas.
look at the mass airflow and all intake boots for leaks, loose clamp.
MAFs dont set codes 70% of the time
ive seen a piece of lint stuck on the MAF meter throw a 5.4 Triton into fits before. shot of carb cleaner blew it off, thing ran like a champ.
dont start throwing parts at it. spend whatever time it takes to diagnose.
ive spent countless hours at work diagnosing a FI problem, no code no nothing. runs like crap blah blah blah.
youll get it.
my moneys on the MAF

 

Try disabling the EGR valve (remove and plug vacuum line to EGR). If that improves performance, the EGR passages are partially blocked. This leads to uneven distribution of EG, and overleaning of mixture. This was a notable problem on 90-93 Accords and 94-97 also.

Agree w/ suggestion to get an ObD2 scanner and check what's happening when problem is presented.

good luck

 

+1 on the EGR

 

Another possible problem is a bad ECT sensor. If the sensor reads cold all the time, then the PCM doesn't know to quit doing the cold-start enrichment.