shampoop

so, i recently bought a 91 gxl. it has had some previous modifications to the mop system and might have had some to the ecu.

so shortly after i got it i realized that the CEL would not come on with the key on and engine off like it should. it made me think maybe it had a cel problem and the previous owner just took out the bulb or something. i've been super busy the past several weeks and have just had the car sitting, so i decided i'd investigate later.

fast foward to today. i went down to the gas station to fill up my gas tank and put in some 2 stroke oil so the system would be ready for when i removed the mop system. on my way home the cel came on under part throttle, i shifted and it went away, then came back again for a little while, then when i let off the throttle to park, it went away again. after i shut it down, i put the key in the on position with the engine off, and the CEL came on just like it's supposed to.

what gives?

keep in mind that i'm pretty sure the mop is injecting it's maximum amount all of the time, plus i put in the 2 stroke oil, so it was running very "rich" on oil. i'm definitely gonna check out the plugs.

shampoop

also, could someone explain this to me? from doing a lot of research i thought all that was involved in removing the mop system was removing it, installing the block off plate, and keeping the ecu out of limp mode. until i found this.

"A proper removal of the internal OMP gear would require removal of the front oil cover, but this is too involved for most people. I've heard a pair of U.S. dimes can be inserted into the hole to keep the OMP gear from sliding around inside the front cover before covering everything up with a block-off plate; if this didn't make any sense to you now, it'll be obvious when you take everything apart."

taken from this link http://fc3spro.com/TECH/FAQ/premix.html

what are the cons to not removing the omp gear?

if there's any real benefit i'm pretty sure i'd be willing to do the extra work in order to accomplish it. the rx7 is a 2nd car, and we just finished rebuilding (piston) engines in school, so i'm not intimidated.

beefhole

iTrader: (29)

Your 91 has an electronic OMP. Even if you remove it, you still need to leave it plugged in or the ECU will go into limp mode. Also, check the FAQs and test your computer for any error codes. That CEL is coming on for a reason.

j9fd3s

iTrader: (3)

there is just no need to do this... when taking out the OMP shaft you also need to plug the oil passage there, apparently without the shaft it will bleed off enough oil to put the bearings at risk.

on an S5 there is very little point to removing the pump in the first place, since you still have to have it plugged in, might as well let it meter oil...

taking out the shaft is a ton of work, if done exactly right, its not an advantage (it takes almost no power), if done wrong you go motor shopping... its just not worth the effort/risk

shampoop

WOW, so i finally got around to removing it.

so when i bought it, the previous owner said when he got the engine rebuilt ~500 miles ago, the shop told him he should either have the mop system removed or "weld it open" and that "welding it open" was quicker and easier, so that's what he did. i mentioned this to some people on here and they could not figure out what they meant.

the car has a S4 mop installed in it with the lever welded on full blast

so i guess the car is running in limp mode. i've tried to keep the rpm's under 4 or 5k because the engine is still in break in, but i did nearly redline like 2 or 3 times and there wasn't any power at the top end. i figured it was the secondary ports not opening because it had plenty of power on the low end and midrange.

so it looks like i'm gonna have to get a s4 block off plate and get the rtek chip.

shampoop

lol, another update. so i just went to remove the ecu to see if i could figure out what "ecu modification" the shop did turns out there was a sticker on the outside that said "rtek7 ecu upgrade version 1.0 installed" so i guess that's $120+ that i don't have to spend, but also means that i still have the lack of top end power to figure out.

i'll check for codes once i get the mop removed and everything put back together.