truck runs bad!

I have an 02 Tacoma with the 2.7engine. It starts and runs rough. If you bump the throttle it sputters and tries to die. If you can get it above idle it runs very rough and will not go above 3000rpm. I've rodded the cat and changed the muffler. I took it to the shop and they said O2 sensore. Changed it. They said fuel pump and regulator. Changed them. They said maf sensore. Changed it. They said tps sensore and exhaust manifold and spark plugs and coils and pvc valve. Changed them. Now it has no trouble codes but still runs bad. I did disconnect the battery cable to reset the computer. What next? Please and thank you.

 

First thing. I also did a compression test 160-170psi. The truck has 230,000 miles on it.

 

I'm sorry I don't know the answer to your question, but I do have a recommendation.

Find a new shop.

They've had you spend a lot of money and not solved the problem. That's never a good sign.

Is this an independent or dealer? Curious minds and all that.

 

Thanks Bill. Its a Ford dealer shop that is suppose to be the best shop in town. No Toyota dealers nearby. And my wife is one of the service writers.

 

Remove, clean, and test your idle air control valve.

Also clean your throttle body while you have it off.

 

Did the fuel filter get replaced when they did the fuel pump/regulator?

 

Yes it did

 

Try a junkyard ecu?

 

James, I've been muddling over this and I have a question and a couple things to suggest.

Does the idle speed 'hunt' ? Never settles, but always up and down? Often a throttle body cleaning will cure that, and of course it's cheap and won't hurt anything regardless.

While you say the plugs were changed, has it been verified each is properly firing? As in the coils and leads are working properly? A dead or skipping cylinder could create your symptom.

Along the same line, is it verified that each injector is working properly, both in its pulsing and operation (fuel flow)

Lastly (actually what I'd check first) I'd be looking for a vacumm leak. Basically you'll be looking for a cracked/broken or dislocated hose(s), or ones that have softened so much they collapse. There are a few ways to test for this, but the easiest/cheapest DIY is visual, each hose, one at a time. It's tedious in a tight or dirty compartment, but worth the effort, particularly on an aged vehicle. You can mark each hose with a bit of painters tape as it passes your inspection if you want to reduce confusion.

If you have, can borrow or rent a vacumn gauge to attach to the motor and get a reading a idle, you will likely find it's not at spec, and that will be another clue that it's part of your problem.

When I say 'inspect', I would include removing and reseating each hose. You may well find that one that looks good will tear/rip when you remove it, meaning it was likely cracked/failing anyway, and you just didn't see it yet. If you run into several, take samples to a parts house and buy a few feet of each size and replace the whole hose, assuming end trimming doesn't get you back in the game.

When the leak(s) fixed, the idle will be steady and the vacumn reading will be both steady and down at the level it should be. I don't know what that number is for your motor, but it shouldn't be hard to find out.

Let us know what you find.

 

When it first started running like crap I did the compression test and hooked up a vacume gauge it was 17 hg and steady. I've tried spraying the intake manifold and vacume hoses with starting fluid. I've pinched and twisted all the vacume hoses. I disconnected my coil connectors one at a time and the engine would die down then pick up when the harness connectors where plugged back in. I did the same with the injector connectors and the same die down then pick back up. Posts on this site say universal O2 sensors are bad and I should go with the Denso brand. Is this true. And the shop said my maf sensor is bad. I installed a Delphi brand maf sensor 6 months ago. Should it have been oem? Oh yea they broke my ignition lock.

 

And no the idle does not hunt.

 

Installed an oem maf and it runs great. Thanks to all for the time and help!