i have a 96 4runner s/c with injectors and fuel management. i am getting 43 psi on the fuel but my exhaust went down the toilet. normally 800-1300 but now 400 at idle and 600 freeway (i had to get home somehow) it actually drops when i give it gas. i have good compression (not as close to each other as i would like but...). my air fuel meter is erradic between lean and rich. not normal back and forth but like all the lights at one time. i replaced the o2 about a month ago. i am thinking injectors but i wanted to confirm with someone. the idle in drive is crap and it runs and sounds the same when given gas. in neutral it idles normally. maybe pushing 40-50 horse power. about 120-160 miles per tank (this is an estimate because it won't go this far..) i do get a slight fuel smell out the exhaust on start up but the af gauge is throwing me off. the egt is saying way too rich or even lean with severe detonation. engine light is on but it has been giving me codes for ever. if its not one thing its another. anyone wanna confirm the injectors or could it be something else? the problem happened pretty instantly within seconds. could injectores go this fast? i am also thinking maf? also anyone in southern california know where i can get same day full service injector cleaning? i don't want to have to ship them out. thx.

 

Are you talking about EGT?


Is this an A/FR on the stock narrow band? What did you replace it with (brand/part #)?


Are you basing this conclusion soley on temp or are you actually hearing ping?


No "but"s... What's the code? What have been the codes?


"Fast"??? Did you replace them? What size are you running?

What fuel management system are you using?

fwiw, 43psi is fine for the stock injectors, but too low for a S/C engine with anything larger. Did you replace the fuel pump?

What were the first signs of trouble?

I would start looking at things like the MAF, TPS, vacuum leaks and fuel pump before I pulled the injectors...

It sounds like you have a hodge-podge of problems... I know how that goes. Did the system ever work well? How long has all this been on?

 

1. yes i was talking about the egt
2. it is a a/f gauge hooked to the front bosch o2 sensor via the wire next to the ecu. i just got this sensor so it can be considered new, but it is old enough that i don't think it is the culprit.
3. i am not hearing a ping but i never did. or even maybe i always had but got use to it as a normal sound but i find that to be unlikely.
4. the codes have always been either a misfire on one of the cylinders, running too rich, running too lean etc etc.
5. when i am talking about fast i am talking about a problem that didn't slowly get worse over time. more like when a transmission blows a gear or your engine blows a rod. it just happens.
6. i am running the super afc 2, with the bigger walboro pump.
7. i am replacing all the vacuum hoses today and i checked the maf with the minimum checks you can do. when i replace the vacuum hoses i am going to check the maf with the oversized one from a supra that i haven't installed yet. but if the maf is not "detecting" air due to blockage or dirt (which i cleaned out) then wouldn't it run lean?

i'll check the actual codes and get back to you. i need to use a different laptop because my palm is no longer doing the job for some reason.

 

There is a long history of trouble with Bosch O2 sensors on our engines. You REALLY need to only use direct OE parts which are Denso's.


It sounds like you've had a generalized fuel delivery problem for a while. How long has the S/C and the piggyback been installed?


And what size of injectors are you running?


Yeah, but you've said that you're "either too lean or too rich", so...

Side note... don't add to the mess by trying to install that MAF. First things first.

What about the TPS? Any chance that you've been over zealous with some intake cleaner lately and soaked it? Check this thread:

https://www.yotatech.com/forums/f123/do-not-underestimate-magic-replacing-tps-throttle-position-sensor-91567/

Also, look around for things like leaks at gaskets; the boost port; is the FPR hookedup? Do you run a boost gauge? (is it swinging from 20inHg -> 6psi?)

Has this system ever run right?


Auterra?

Also.. I figure that you've pulled the EFI fuse to reset the ECU? It'd be cool if we could troubleshoot one code at a time... So, reset the ECU, run the truck and wait for a code. Grab the code(s) and let us know what it(they) is(are).

 

2. ok. my bad. it was in fact a denso. i had to recheck urd.com which is where i bought it to make sure. the s/c and piggy back have been on the vehicle for about 50,000 trouble free miles.

4. i never had it dynoed for power but it did seem that i wasn't getting all this power everyone is talking about so it is possible it hasn't been right for a while. (maybe i am just hard to please)

6. i currently have the injectors in for cleaning to make sure they are running at full 305 capacity which is what i believe the supra injectors are rated. it has been a while since i got them and they were of course mildly used.

7. i WAS only going to change the maf to see if some of the drivability comes back. it seems that the resistances are good and i did clean it but to no avail. i am currently cleaning the crap out of the throttle body right now and checking the resistances of that. i had not used the injection cleaner before so i don't know about it being soaked. after reading that link, thank you by the way, it does lead me to think that the goop from the pcv valve maybe did something to it. i got a lot of crap inside of the tb and s/c. i just bought the parts to install the air water separator mod that i see a lot of lately.

i am also checking the valve clearances today as well. my car does have 170 miles on it without too many problems so it is definately in need of some of some care on the hard to reach parts..tbs, vacuum hoses, etc.

 

Wasn't there a problem on someone elses 4rnr s/c a while back. Alot of parts were replaced,never helping the problem. It ended up being a clogged cat.

 

ok. 10 minutes later. i rechecked the maf and the tbs. the tbs is way off. i get an open lead somewhere close to 75% full throttle. it won't go past 2k ohms which is the minimum for full open. i imagine that once i took it off completely it shouldn't change things much except for the fact i could not apply vacuum. still no change. you are supposed to test 3 ways and 2 of them failed. it also seems this is a part that could fail "quickly". ill get a new one, finish with the other repairs and let you know in a couple of days. thanks for saving me tons of time from having to go and test everything in the fuel system. the tbs is one of the last checks. kinda like christmas lights.

 

Funny, that was the first thing that came to mind, but I misread "fuel smell" and thought it said "foul smell".
It still might be a clogged cat causing this issue, but I'll let Mark and company help eliminate the other items first.

It does sound like this was an ongoing issue, but another problem (possibly TPS) sent it all over the edge.

 

ok. so i bought a new tps and tested it. i ended up returning it because it gave all the same results as my old one. it looks like i am going to have to wait until my nosedrive and injectors come back. i am currently changing my timing belt (just because) right now. whereas i would have liked it to be something that simple i don't think it is. and it wasn't a misspelling, it actually is a fuel smell. so i don't think the catty is bad. i might replace it anyhow because its getting old and i want a new exhaust system..

 

Have you hooked up a laptop to the AFC and verified that your fuel & timing maps are intact? Every-so-often my SMT-5 will puke due to low voltage and dump the maps and the global config. That was fun to diagnose the first time it happened.

Along those lines, you might want to try bypassing the AFC (I figure it sits in the MAF signal?) and see if things get "better" or even if the symptoms change at all.

TPS wise... did you actually try the new one before you returned it? My original TPS tested fine, but a DMM couldn't show the flakey connection between the wiper and the ring. A 'scope would have, but I didn't have one handy.

 

i actually solved it last week but i went to vegas and didn't feel like getting online there. so so sorry. the culprit.....drum roll.....spark plug wires. WTF??? it only took so long because i felt like doing a bunch of other lingering things that would have taken my truck out of service for a while anyhow so i was waiting for a time like this. i replaced the t-belt which was no easy chore with the stock belt being on after 166k miles. it was in great shape and would have lasted another 50 easy. after screwing around with that friggen bolt for a day and half i finally got it off. a 500 lb impact wrench wouldn't do it so i bought the biggest one possible a 600 lb impact wrench. that thing was worthless. i had to do the old fashion way....for 12 bucks. i cleaned the injectors and i am happy to know they are running great now which is a good feeling because i bought them used for 50 bucks and didn't have them cleaned when i did. back to the problem. no tps, no maf, no ecu. the culprit was some very very very small holes in the rubber of the spark plug boot on the drivers side. they turned white when i pulled the boot off the plug a way and cranked the engine. this was by accident but i heard the spark jumping. there was no way that spark would have went out the hole down and around so i took a closer look. that would definately explain the low egt temps since the sensor is on that side. it would also explain the misfiring code i got. i was trying other stuff to fix that code but didn't think of wires because they only have like 10k on them. total cost with tools, cleaning, belts, vacuum hoses and everything? about 600 bones. i will definately make a write up for my new nut remover for the flywheel nut.