abadgti

Figures it would happen to me, but I just purchased a 1990 4runner SR5 Monday and yesterday I noticed at idle the dash would shake. When i started driving it felt like it had no power. Today I replaced the wires, plugs, cap, rotor, checked all vacuum lines and its the same. When I got it on the highway and tried to accelerate above 70mph the whole truck shook.

I don't have a timing gun so I haven't checked the timing yet. The PO put $10 worth of 93 octane before I bought it. I ran it dry and filled it up with 87 octane. He also said that he would alternate between 93 and 87 in the 8 months that he owned it. My next guess is to replace the fuel filter. Is there anything else I should check? Thanks in advance.

MuddinRI

Yes I Bought a 94 P/U and found after a month of driving it with the same problem that the cat was completely jammed up. It was so bad the element inside had rings from the exhaust trying to flow. you should def do the fuel filter and or a complete tune up including checking timing for sure.

yoterr

sounds kinda timing related, is the check engine light on? also what motor is this? the 22RE? i would try the fuel filter and put the 93 back in it and see if it helps, also are the manifolds getting red hot??

abadgti

No check engine light and the motor is a 3vZE 3.0 V6. Manifolds are not glowing red.

I just took off the airbox to clean the MAF and the small box with the vacuum lines running to it was cracked. I put some tape on it used for HVAC and hoping that fixes it.

Next step is checking for a blocked cat.

abadgti

Replaced the fuel filter. I thought that would fix it because the gas coming out of the filter was brown.

Is there a DIY for setting the timing?

jmoore9982

First - Have you been out rock climbing with it? If so check and make sure that you haven't damaged the cat, muffler, or tail pipe. If there are visible signs of damage replace. If no visible signs, take the cat loose and see how she runs then. If it runs good with cat off, I would go with a whole cat back exhaust system. This could also be a timing issue, but if it was running good and you didn't change the timing it shouldn't be that bad. You may also want to check the flow rate on your fuel pump.

abadgti

I haven't been offroad with it yet. I did find a small exhaust leak in the tailpipe, but I don't think that would cause it.

How do you check the flowrate of the fuel pump?

Thanks

abecedarian

How did the old spark plugs look? Have you verified the spark plug wires are connected in the proper firing order?

abadgti

Spark plugs were corroded and definitely needed to be changed. I was poking around in the engine bay today and noticed that the two marks at the top of the distributor didn't line up so lined them up and now its running like it did. The only other issue I need to sort out is that in Park it idles at 1300 RPMS. Sometimes it will jump down to 900 and then back up again. Any ideas?

Thanks for everybody's help and im so happy that I got it running right again. We planned a 3 hour trip to Ocean City MD this weekend so hopefully nothing will go wrong with it again (knocks on wood).

yoterr

ur idle is set too high, and once it reaches a certain rpm the ecu compensates and kicks the idle down, causing surging, so jut idle it down i think for 22re's its like 750 or 800 RPMS

abadgti

How do you set the idle in a 3VZE?

abecedarian

The ECU does not have much if any direct control over idle speed, meaning the ECU does not adjust the idle speed for the sake of adjusting the idle speed. Idle fluctuations are typically caused by vacuum leaks, ignition timing, ECU being in closed loop mode when it should be open loop due to throttle position sensor, etc. and any adjustments the ECU makes to fuel mix, timing, etc: the idle speed is the result of these adjustments, not the reason the adjustments are made. Make sense?

Idle speed can be set by turning the large screw on the throttle body at any time, but generally it should be set with the computer in diagnostic mode so that the ignition timing can be adjusted as well: timing and idle speed are inter-dependent.

yoterr

mah bad, i was just relating info i read on a thread a while back

abecedarian

I understand and wasn't trying to chap yer hide or nothing.

There are only 3 'real' things that effect idle:
1) throttle plate position (this is determined by the little set screw on the bottom of the throttle body)- this is the basic adjustment for idle and everything depends on this being correct... and this should never be adjusted since it is technically a specific adjustment to and for the characteristics of throttle body. Tweaking this can and will effect every other thing that depends on throttle position from the throttle position sensor to ported vacuum sources for EGR, A/C, Charcoal Canister Purge, and possibly even Cruise Control operation.
2) auxilliary air valve / idle air valve (AAV/IAV)- a temperature dependent valve that lets air around the throttle plate when the engine is closed and restricts this air as the engine warms up. Think of it as a valve that pretends to be your foot when the engine is cold and causes the engine to idle higher when the engine is cold... kind of like the choke on carbureted vehicles did, but slowly closes as the engine warms up until it's completely closed and the engine idles at the prescribed RPM's.
3) idle bypass screw- a screw on the throttle body that allows air around the throttle plate. Well, this sort of overrides everything, to a point. This should only be mucked with to set the warm idle speed since the AAV/IAV sets the cold speed and the throttle position stop shouldn't ever be touched. If adjusting this to set warm idle set properly results in poor cold idle speed then the AAV/IAV may be a culprit, i.e. the AAV/IAV may be sticking, stuck or otherwise blocked in either of the air or coolant passages allowing either not enough air to bypass the throttle when the engine is cold or too much air to bypass the throttle when the engine is warm.

Obviously, timing and coolant temp also effect idle speed but the ECU can't change coolant temp on a whim, and timing is set in response to various sensor inputs, one of which is idle speed. This, somewhat paradoxically, makes idle speed a result of what the ECU reads from sensors and engine timing, not something the ECU tries to adjust.

Guess I should also include the a/c idle up valve but it should only affect idle speed when the a/c is on.

yota_mota

Wow, you're just a wealth of knowledge are ya? Are you a tech? If not I hoper you at least make more money than they do. What part of SoCal are you located?

abecedarian

My mechanic history has been debated many times so I'm not going to go in to it here. I don't get paid for what I contribute. Suffice it to say I've been certified as a diesel mechanic, done 95% of all the mechanical work to all of the vehicles I've owned since around 1984 from a Dodge Dart, Chrysler Laser, air and water cooled VW's (incl. diesel), Toyotas, 72 Firebird, and even an 82 Honda turbo motorcycle.

I'm in the Temecula Valley area of SoCal.

abadgti

It idles at 800 when it's in gear, but in Park or neutral it idles at 1200 when warm and 2000 RPMs cold. Any idea what needs to be adjusted?