I just picked up a 89 pickup SR5 4x4 3.0 263k on the clock, runs almost perfect. I'm the second owner and have put about 600 miles on it so far. So now on to my question.

I just put a new exhaust system on cat/muffler since it was the original system on it and it was suspect of restricted flow. But I have a slight hesitation on lower rpm's from about 1500-2500. It also has a small ping/chatter on acceleration only. I also still have a stinky cat smell when going up hills even after the new system. I was suspect of the timing so I bought a timing light today, and I'm sitting at a steady 10. Could the advance on the timing be causing my problems. It had a new timing belt installed by toyota about 40k ago. So I would have thought it should have been set right from them? Anyways could out of time cause these issues?

Also a few things to note. It idles perfect and steady at 750. Floats down the highway in 5th fine and pulls descent hills without slowing down. Gets pretty descent milage also, right about 300 miles per tank. All stock from what I've learned from the dealer who took in on trade.

Any help is appreciated.

 

10* BTDC is exactly where the timing on your 3.0 should be. What size exhaust did you put on? If you are running anything larger than 2.25", your low end power will suffer.

 

Ah ok I thought read somewhere 0* but who knows I haven't bought a book yet and I need to. I went with a 2.5 inch exhaust and it seems like my power has gotten better. But the problems I had where there with the stock exhaust too. It also has not thrown any codes to me either.

Thanks

 

How's your fuel filter? Has it ever been changed?

 

10 BTDC is stock but 12 BTDC works better for me.

 

The fuel filter was changed by toyota by po about 20k ago. I have one sitting in my garage ready but I was unable to change it since I could not find a suitable plug and I was leaking gas badly.

So what does the extra advance give you? and how do you change it? Rotate the dizzy?

 

Thats the region where the EGR valve is active, it may be normal.

Edit: If you want to see if the EGR valve is suspect, remove the vacuum hose connecting the top of the valve to the vacuum modulator, and give it a test drive. It is likely that this may alleviate your symptoms, but it will also confirm that this is normal operating conditions for the engine.

- I run my engine at 16 deg advance.

 

many people report 12-15 deg as running better with better pickup. Many equate this to toyota de-tuning the 3vze for better fuel econimy.

 

when you talk about 10-15 deg is this while the engine is at idle

 

Yes. Once you've jumped the two terminals mentioned before you need to loosen the bolt that holds down the distributor and then start the truck. Don't forget to use chalk or a bright permanent marker to mark the timing degree you want to try.

With OBD III on cars now a days using a timing light is becoming a lost art. If you are still not sure find someone older in your family who knows how. Once you explain the jumping of the two terminals (does the same thing as disconnecting vacuum advance on old cars) then they'll show you how easy it is to do. I'm considering going up to 14 very soon but my check engine light went on last night. Judging by the real good fuel economy I've been getting I think I'm running lean so its likely the O2 sensor will come up when I get the code read.

 

Sorry to hijack, but is there any good threads on how to check timing or how to check/inspect the timing belt?

 

inside your air flow meter is a potentiometer.

this has a carbon rail on which a needle rides and reads resistance. this carbon rail can and will wear out. so, long story not as long as it can get, try a new(er) air flow meter.

as its not repairable (well, not unless you have a medical soldering iron)

but.
1st try
cleaning the throttle and intake w/electronic cleaner (safer than brake fluid) sometimes the varnish can build up on all those parts.

also
check for vacuum leaks (250000 is a ton of miles)

start w/the small stuff, adn work into the AFM, as that will be more than 20 bucks