4runner316

I got a 1990 4runner 4wd, auto, 150k miles. About a week ago she starting running real funky. It used to only do it when the engine was cold, but now its doing it all the time. As soon as I start her up, the exhaust sounds different. Kinda like a tractor and it sounds like "popping" sounds inside my exhaust. (There is no holes or anything). If I go under the hood and rev her up, the engine itself sounds normal. When I start driving it runs like crap. Poor/choppy acceleration and lots of bucking. When I am crusing on the freeway it basically feels like I am lightly tapping the brake pedal every few seconds.

It is sort of intermittent. Every so often it will start running like normal, but then it goes right back to running like crap. Right when all this starting happening, I noticed the smell that she is running very rich. My gas mileage confirms it. From my understanding this is definitely a fuel injection issue? Any hints of where to start at? She just had a tune up done right before I bought her. New plugs, wire, cap and rotor and fuel filter. Any help would be very appriciated. Thank you!

yayfortrees

I like how you give all the extra, unnecessary information, and didn't tell us what motor you have. That's great.

Regardless, have you checked for any check engine codes? And are you sure your engine light works?

Sounds like this will probably be a sensor related problem. I would start by getting yourself a manual and a multi-meter. Make sure the meter has ohm capability, because you will be using that a lot. Then, start checking resistances of all your related sensors and wires and connections. Sensors to check would be O2 sensor, AFM, TPS, etc.

If all those check out, you might have a leaking injector.

4runner316

My bad. She is a 3.0 V6. Thank you for the help. As far as I know, my check engine light works. It lights up when the key is in the ignition mode. How do I check for codes? Could it be possible that there are codes without the check engine light coming on? Also, will I need a factory service manual or will a haynes manuel do?

Thank you!

yayfortrees

This link will give you all the information needed regarding the codes:

http://www.off-road.com/toyota/tech/codes/index.html

Sounds like the light is working properly, and I think sometimes it can store a code without the light being on.

There used to be a link to download a manual, I don't know if it is still active or not. The sticky thread is still there towards the top of the 86-95 page in this forum. If it's still active, it should be the factory manual, which is better than the haynes. From what I've read, there is some information that is only contained in the haynes, and some that is only in the FSM. While I have not confirmed this myself, I think the FSM is the best, and should give any spec that could possibly be needed.

Keep us posted, and feel free to ask if you have any more questions.

Edit: By the way, are you in KS?

Joebear

I'm having the same problem with my 95 4-runner with the v-6 3.0 engine. It's just got really bad. The Check light works. I'm going to auto zone today. They will check it for codes free.

If you have any more solution, post it. I'm concerned it could be a fuel pump going bad.

dark_fairytales

first thing i would replace is the O2 sensor if it is close to 12 months old. in general the O2 sensor is suppose to be replaced every year or 60,000 miles.

Kiroshu

May want to look at your Air Flow Meter. Check it for OHMs using the FSM. Does the "flapper door" open and close nice and smoothly? Airfilter dirty? Timing? Check timing belt marks. Got enough coolant in the engine? Coolant temp sensor? Do you fix and replace anything that this may have started after the fact or was it random happening? Or has it always been there but getting worse. Tried "slapping" the AFM?

ChefYota4x4

iTrader: (5)

These guys are right, 316,

You really have to pull the codes, and you can do this, easily, by yourself, ...but if they'll do it for free, that's not a bad deal. My guess, considering my 4Runner was doing very similar things(popping and pupping) before replacing the O2, is that it could be just that, ....o2 sensor. GET DENSO(Tell the dealer you went on their site and it's listed at like 128$, ....mine give me the website price, instead of the 186$ THAT THEY'RE ASKING!LOL), do NOT buy some AutoZone or Napa model. I put in a bosch and IT DID NOT dial in right with the ECU. Also, read the TPS testing directions CAREFULLY, they're included in the Haynes, which is also at Autozone(Multi-meters are not expensive, GREAT TOOL...ask while you're in Autozone for one). However, adjusting the TPS can be more tricky, and you can find links on this site for adjusting it. I believe it's a link to 4crawler dot com. Coolant Temp Sensor can also cause this problem.

However, eventually, if you've eliminated all the sensors, you need to start thinking fuel. I had 2 BADLY leaking injectors and my Cold Start Injector was leaking as well, ...the latter caused it to run rich long into warming up.....Remember, RICH=DESTRUCTION OF CAT, QUICKLY, so fix this asap, ya know? CAT's aint cheap.(UNLESS you're not in CA., like me! lol....They're much cheaper everywhere else, .......ahhhhhhhh, lol)

ChefYota4x4

iTrader: (5)

Have you slapped yours?....and did it work? lol....I only ask because I can't figure out my problem, and the dealer friend I have thinks it's the AFM.

Good luck, 316!

4runner316

Alright guys, I think I might have narrowed it down to the AFM. I just want to run this by you guys before I dump the money to get it fixed. I tried "slapping it", but it doesn't resolve my problem. It looks like mine was modified at one time or something, there is somekind of sealent all around the top. I'm guessing it was either replaced or remanufacted at some point and they didn't put in a new gasket, so they just sealed the top off with sealant. Here is a pic.


According to the Haynes manual, the ohms are off and needs to be replaced. If I measure terminals "Vs and E2" I get nothing. Can somebody confirm that theirs DOES measure an ohm reading at these terminals? There are 7 prongs. The fifth and sixth prongs would be "Vs and E2".

I almost had a heart attack when I got a quote from the dealer for a new one of these. Yeah... Almost $1000!!!! Autozone has a remanned for $200.

Thank you!

Kiroshu

Eww Replace it. Never good that its been opened up.

Yes if the Ohms reading was ANY bit out of spec the AFM meter is considered bad and needs replacing. Yea at the dealer its like 900$ soo.... if your on budge get one at a local parts store pref pep boys,napa, but autozone and advanced are ok...... o'reillys doesnot even carry it...

thook

Sorry, but that part's fine to open up. You can adjust the air/fuel mix in there, but that doesn't mean it's not out of whack from being tinkered with.

Autozone........just be careful. The only good replacement they have are the units that actually say Denso on them. The other in house brand is garbage.

Kiroshu

Eh i dunno what kind of luck you have had but i've had dozens of problems with tampered AFM's that needed replacing. You are to never even adjust Air fuel mixture or idle screw on a fuel injected vehicle. If theres an issue it needs to be found and repaired not just go out and idle it up and drive.... I hate that those screws are there at all....

thook

Oh, it can come in handy and even be necessary if someone's modified the compression ratios when rebuilding and you need to richen the mix. I've done it before just to get the vehicle to run mostly right until I found the real problem. Then, you just set it back. It's not really a problem. I suppose it can add to the headache, though, if it has been messed with, you don't where it's supposed to be set, and you have no idea what the real problem is.

Kiroshu

^Ah now i see...... But see I'm Mr.OEM i don't mess with much after market mods and racing stuff lol. I like everything OEM..... And to keep a car OEM you are never supose to adjust the screws. Believe me i have screwed a few idle screws for ppl who were like "just idle the B%^t&h up so i can go to work"...... I'm like.... Oook...

TOE-B

mines doing the same thing same 3.0 v6 4x4 auto......... heres what ive done so far and still get CEL that reads EGR. ive replaced....plugs, wires, d cap, rotor button, coil, egr, egr modulator, vsv valve for egr, tested tps and readjusted, also pulled front cover to check timing marks and checked timing, and the idol was way up so i adjusted that. today i checked the afm it was in spec so i cleaned it and reinstalled. and i put a new gas cap on. 20 miles after the cel was reset BAM right back on. someone said o2 but the only code im getting is egr! but mine is acting the same way bucking a litle it will idol fine and smooth, but when you are out on the hwy its almost like you flip yhe switch off and back on again real fast. when i bought the 4runner a few weeks ago it had been sitting on a lot for a few months. is there anything else you guys might could tell me to check im all out of options????????

sorry didnt mean to hijacck a thred!!!!!!!

ChefYota4x4

iTrader: (5)

Not sure if it's "N/A" on yours, as mines a 22re, ...but do you have a BVSV? That controls vacuum to EGR on mine at warm temps but shouldn't have vacuum at cold. Easy test for it, if you have a Vac. Pump and Gauge. It reads by coolant temp. Just throwing it out there. Good luck.

4runner316

Well, I replaced my AFM with a remanned from autozone. They were the only one in the area with one for a decent price. NAPA wanted $600 for their remanned. I got mine for $200. My new AFM is now within the correct ohm readings, but the bucking and popping and running rich is still going on! I think my next step is going to be the o2 sensor. I know a bad o2 sensor could be the popping sound - but what about running rich? Can a bad o2 cause a vehicle to run rich? Can somebody tell me what the ohm reading should be for the o2 sensor and what terminals to check? I have the fuel section from a Haynes, but not the emissions part. Thank you!

ChefYota4x4

iTrader: (5)

600$??? That doesn't seem right. Might be because it's a diff motor...but my quote from Napa HQ(where I have an account) was 199$. Something seems off there.

Anyway, you've disconnected the ground I'm assuming, to reset the codes, and you're not throwing a code for anything? I believe the O2 throws codes most often, mine did, but can't hurt to check, you're right. Might want to recheck the ECU terminals, I'm about to do that on mine. Curious if you have that BVSV I asked about in the above post? You said you're throwing EGR codes, and that is VERY MUCH related to the EGR(you have a wire for your EGR, right? Just asking, cuz I don't)

yayfortrees

LOL! Adjusting the idle screw is not going to make a vehicle not OEM. The ability to make fine-tune adjustments are absolutely necessary for any mass produced vehicle. Do you really think they can stamp out thousands of throttle bodies that idle exactly the same without any fine-tune adjustments?

I realize that we are talking about Toyotas, but most motorcycles and ATVs can be adjusted to run much better by adjusting the air/fuel screws differently than how they came stock. Manufacturers (Toyota included I would imagine) have to pass certain EPA specs. A common way of doing that is by making the motor run slightly lean at a certain RPM. It gets it to pass EPA spec, but is not optimal for smooth running or throttle response.