Car not accelerating when going uphil (popping and rattling sounds)

[el_chapu-bling]

*** I posted this in several threads, but since people do not want their thread "jacked", I'm posting it yet again, to get more attention ***

Here is what is happening to me. I have a 2000 4Runner 2WD, V6, automatic. I bought it last December (had it for about a year). I got it with 64K miles, I have reached 84K this week -- about 20K miles in one year...

On to the issue:

- I first got a CEL last month going up hill to take a freeway onramp. I didn't feel anything different with the truck, just that the CEL light was ON. I took it to a friend for a computer diagnosis; it was the O2 sensor (the "first" one, before the cat)

- I get it fixed. CEL goes away. The next day, the CEL turns back ON again! I take it to my friend once again. It appears to be the MAF sensor. He cleans it, as well as the throttle body. CEL goes away again.

- Two days later, CEL comes back ON. The MAF sensor needs to be replaced. I get it done and the CEL goes away (again).

- Everything is cool for about 3 days, when all of a sudden, the CEL comes ON yet again (for the 4th time, I believe). At this point, the truck feels no different than when I first bought it. It's just that the CEL is bothering me and I want to get it fixed...I keep driving the truck for one more day (it was a Sunday) and on Monday during lunchtime, the CEL simply turns OFF...

- I keep driving the truck with no issues until a couple of days after the CEL turned OFF, I reach a stop light facing downhill. I am just stepping on the brake while on "D" (Overdrive always ON). The truck begins shaking a little bit, as if the engine was losing "pressure", if you will. The light turns green and I accelerate, make a right turn and start going uphill now.

The truck is not accelerating and it feels like it's choking. I press the pedal even further and I start hearing some "popping" sounds coming from the right frong underside of the car (kinda where the O2 sensor is). I release the accelerator and step on it again, wanting to get the car out of that "choke". The truck now starts responding and accelerates very fast. Truck returns to "normal"...

- I take it to my friend again, but this time the computer shows nothing wrong. WTF? He tells me to keep driving the truck to see if it happens again. Keep in mind the CEL has been OFF all the time.

- This same thing happens again a couple of more times. Now it's time for an oil change and I also do the fuel filter change (NOTE that I had done a "tune up" to the truck on the last oil change, 5K miles ago).

- I keep driving the truck thinking this will "solve" things and nothing. The truck did it again, but this time it lasted longer for it to respond. The weird thing is, that it always happens when I am at a stop light facing downhill and have to go uphill after the light goes green. At the stop light the car would shake, RPM start going up and down below 1K similar to when the battery or alternator is bad--Once I start accelerating uphill, the truck does not respond and moves very slowly. The more pressure I apply to the pedal, the harder the truck "chokes" and the more air "popping" sounds I hear.

I am not a mechanically inclined person, so I am just describing things as I feel/hear them. The truck honestly feels like its being blocked of air, like something is being blocked and the car cannot advance. It does not feel like transmission/engaging problems (I have a Mustang where I had that problem, not the same) nor like engine internal issues. I really hope it's something very simple or something just got stuck in the Air ducts.

I want this fixed! I have been losing a lot of time and money now trying to get this out of the way for the past month. I am sure somebody has had the same problem I do! Please help!

I thought 4Runners were "indestructible" and very reliable as I have been told by 99% of the people I talked to before buying mine. I have a limited power-train warranty from the dealer until I reach 100K miles, but I doubt they cover stuff like this. Plus, they charge an arm and a leg just for "diagnosing", and if my friends computer did not come up with anything, I doubt the dealership will be able to tell me otherwise...

Thanks.

 

[MARSHALLMAY]

make sure there is nothing unpluged under the hood, check for blown fuses and make sure all relays work. if you can't get a professional diagnosis, then just start replacing parts. but i would start with wires plugs and coil packs. fuel pressure regulator, check you throttle position sensor...

 

[tahoerdr]

What code came up when your CEL came on? Does the popping and rattling sound like grinding suspension components, or more like engine ping or backfiring? Engine ping sounds like there's a coffee can with marbles in it rattling around in your engine. It wouldn't hurt to power cycle your EFI system, especially since you replaced so many comonents. To do it, first disconnect the neg. battery terminal. Remove the 15amp small fuse for the EFI under the hood. Press on the break pedel to drain any remaining charge in the system. Wait a few mins and reconnect the fuse and battery cable. The car will run rough for a couple miles but will adjust. This will make your fuel trims closer to where they should be.
I have a similar problem:
I've had a problem with a code coming up that read "MAF sensor circuit malfunction". It would come on only when under full throttle@high RPM or cruising for a long time on the highway at +2,500 RPM going 80mph. The whole car would jerk once as if choked for air. One time the pedal did nothing at that point, and I had to cruise through an off-ramp. I floored it and it jerked back to life after a second. The MAF (hotwire type) was dirty so I used some electronics cleaner fluid and paper towel to clean the hotwire. I also replaced the aftermarket Injen air filter with a new Apex'i. It still happens under extreme conditions but much less frequent. I'd really like to find out what what's wrong...maybe our two problems are similar.

 

[mikes4runner]

Maybe a bad Cat converter?


Mike

 

[tahoerdr]

RE: Bad Cat

Ya there's a good chance that it's the cats. I've got the URD fuel upgrade kit for my S/C but different sized injectors so I've had trouble tuning it--I have to build the fuel map myself. Ran pretty rich and also lean in a few areas for a while...according to a muffler guy, it can take as little as a teaspoon of gas in the cat to toast it. They're a nice bronze color from the heat now.

 

[el_chapu-bling]

Thanks for the advice to all

I also was told in another thread that it might be the spark plug cables. I guess I'll have to start replacing stuff from cheapest to most expensive, and see what "fixes" the problem.

I will post updates.

Thanks.

 

[makakio]

Noooo - I disagree. Just go to a good, reputable tech. Ask here for a local Toyo guru and take your truck there. Guaranteed to be more cost-effective than starting with cheap stuff and "working up". A good tech should be able to figure this out over an involved conversation and test-drive.

 

[el_chapu-bling]

Noooo - I disagree. Just go to a good, reputable tech. Ask here for a local Toyo guru and take your truck there. Guaranteed to be more cost-effective than starting with cheap stuff and "working up". A good tech should be able to figure this out over an involved conversation and test-drive.

Ok, after procrastinating for the longest time (actually, it was because the truck had not given me same problem until a couple of months ago) I took the car to the dealer to have it diagnosed.

They told me the MAF and Air-Fuel Sensor were giving me bad readings and that the MAF had a "surge"--the air filter and spark plugs also needed to be changed (done with an oil change). This was not covered by my power-train warranty, so I decided not to have the work done there. The technician said that the MAF was not completely "bad", but that it was giving low readings (Maybe something else causing this?)

Here is the strange thing, I had already replaced the MAF on my car back in October of 2005. I bought it from AutoZone, and the 3-month warranty had already expired. Are the AutoZone MAFs so bad that they stop working within 4 months? In any case, I doubt the MAF itself is causing the problem since the problem was there before and after I had replaced the MAF (in October). I had told this to the tech, but he recommended (like every dealer) to only use Toyota OEM equipment/parts...

Question #1. Are Toyota OEM parts really worth it?

Now, all this leads me to think that it is really the A/F sensor, but I cannot seem to find it at any autoparts store--just my dealer, and it costs $215!

Have any of you guys replaced this Air-Fuel Sensor? If so, how much did you get the part for and where?

The car runs smoother now, but it has already done that malfunction (jerking, air choking) twice since I visited the dealership. I can't believe I'm the only one with a 3G 4Runner that has this problem!

Thanks.

 

[lookn4runr]

I would be skeptical of an aftermarket MAF. My money would be on a Toyota part fixing the problem!

 

[makakio]

Hmmmm. Well, I believe the MAF can be cleaned to some degree (mine was at the 90k service by my tech) - and that dirt/oil (sometimes from over-oiled aftermarket air filters) is often the cause of bad MAF readings.

I don't know if the air-fuel sensor can be cleaned up and restored to good readings, but if it were me - and with a diagnosis in hand - I'd just buckle up, buy the OEM Toyota parts and install them.

It really is your best avenue to a fix. Of course you'll want to do the spark plugs and air filter too as it doesn't sound like new sensors are going to completely resolve the issue.

Car ownership sucks, eh? Listen to this: I have a 2003 BMW that's about to go out of warranty and I'm electing to buy a $2250 extended factory warranty on it because in the first 45k miles I've had about $4k worth of faulty electronics (mainly sensors at $600 a pop to fix) replaced on the damned thing. So yeah - I'm spending $2250 on the premise that the car is going to cost me at least that much (plus inflation) in repairs over the next 50k miles/3.5 years. I hope that helps add some perspective to your (likely one-time) repair bill.

FYI - the AutoZone MAF should have some kind of warranty attached to it. You may be able to take it back with your tech documentation and get a refund.

 

[el_chapu-bling]

Hmmmm. Well, I believe the MAF can be cleaned to some degree (mine was at the 90k service by my tech) - and that dirt/oil (sometimes from over-oiled aftermarket air filters) is often the cause of bad MAF readings.

I don't know if the air-fuel sensor can be cleaned up and restored to good readings, but if it were me - and with a diagnosis in hand - I'd just buckle up, buy the OEM Toyota parts and install them.

It really is your best avenue to a fix. Of course you'll want to do the spark plugs and air filter too as it doesn't sound like new sensors are going to completely resolve the issue.

Car ownership sucks, eh? Listen to this: I have a 2003 BMW that's about to go out of warranty and I'm electing to buy a $2250 extended factory warranty on it because in the first 45k miles I've had about $4k worth of faulty electronics (mainly sensors at $600 a pop to fix) replaced on the damned thing. So yeah - I'm spending $2250 on the premise that the car is going to cost me at least that much (plus inflation) in repairs over the next 50k miles/3.5 years. I hope that helps add some perspective to your (likely one-time) repair bill.

FYI - the AutoZone MAF should have some kind of warranty attached to it. You may be able to take it back with your tech documentation and get a refund.

I already asked at AutoZone when I went for spark plugs if they would do something about my bad MAF, but they said the 3-month warranty was already expired...I guess I'm SOL on that one.

The Toyota MAF costs me $169 at the dealer, plus $215 for the A/F sensor.

Do you guys know where this A/F sensor is located in the car and if it's easy to reach? Or is there some removal of parts/components involved?

I just want to buy the part and have it installed somewhere else than the dealer.

BTW, the Air filter and spark plugs have already been replaced last week. The truck does run smoother, and I've yet to feel the problem again. I took my truck to my friend yesterday to have a "second opinion" on the diagnosis and indeed, the MAF is giving low readings. However, he doesn't know the code to check for the A/F sensor readings. He's going to find out and give me a call when he finds out.

Help?

Another thing, since I have not felt any problems (yet) after the air filter, oil and spark plug change/replacement, should I wait it out a couple of weeks to see how the truck behaves before actually spending about $400 in parts (MAF and A/F sensor)? Then, if it does it again, I will immediately buy the parts to see if that will FINALLY fix the damn problem...

 

[makakio]

Two things to consider:

I think this depends on what your time/money/patience continuum looks like. My time is worth about $80/hr, so if someone diagnosed the problem as a bad MAF and AF sensor then I'd just replace it b/c waiting and troubleshooting it on my own time would in effect cost me more than the fix.

Also, if the readings on the MAF and AF sensors were resulting from a bad air filter and sparkplugs - and I wasn't having the problem after replacing those - I'd see if that corrects everything before spending $400 + labor.

Good luck

 

[lookn4runr]

If the dealers diagnosis says the MAF and A/F are bad, and this will correct the problem, I would let them do it. Then you have the recourse of "You said this would fix it" . If you have the parts installed by a third party, then all bets are off with the dealer. If you continue to have problems, you are no better off. It is really best in my view, to have someone work on it who does so regularly.