Chugging on start becomes not starting at all, unless I push the gas

I have a 1998 4-cylinder 2.7 liter Tacoma 4x4 extended cab pickup, 260,000 miles. It's been a little chuggy the last month or so when I start the engine, I thought due to an exhaust leak that I'm scheduled to have welded in a couple of weeks. Then, this afternoon when I went to start the truck it turned over and caught but then immediately died after some tortured chugging. Pushing the gas hard while turning the key seems to work and the truck keeps running after, but I'm not sure about driving the truck any distance, or whether this is an OK interim solution in the two weeks leading up to my appointment. It's my only car and I live 14 miles from the nearest town.

Two questions:

1) What might the problem be? (Could it be something as simple as the aftermarket K&N air filter needing to be cleaned?)

2) Could I cause further trouble by driving it the 24 miles to the mechanic after forcing the start? Should I have it towed?

Thank you!

 

I'll take K&N oil fouled MAF for $100, Alex

I don't think it will do any more damage

 

I agree with Craig, sounds like MAF sensor is dirty.

 

Thanks all--alas, the mechanic thinks my first cylinder is starting to go. Compression has dropped to 120 PSI, while the other cylinders are still running at 160 or so. He wasn't sure why the truck would have struggled to start. He's doing a leak test to see if it's something smaller than the motor wearing out, like a problem with a piston ring. Fingers crossed, but it's not looking great.

 

IAC clogged?

 

would that cause the loss of compression?

 

No. I'm not convinced 37% psi loss in 1 cylinder is your problem

 

If the valves have never been adjusted then it isn't uncommon for a burnt valve at 260k miles. That would explain the loss of compression. Check the MAF like said and check/replace the #1 spark plug and see if it starts better.

 

right--it may well be that he discovered the engine was going out while looking for the thing that caused the rough start. But the latter seems less important, if the former is the case? When he checked the engine, he got two misfire codes, and the spark plugs and wires all seem fine.

 

Any reason to replace plug #1 if the plugs and wires all look fine? Maybe it is just a burnt valve, on the engine stuff.

 

$4 piece of mind.

 

haha--good point. Definitely cheaper than a new engine, or a different truck

 

when its really cold out (single digits and below). i have to hold the throttle down on my truck and rev it to 2k for the first 15 seconds till its running/warmed up enough to idle.

i can go spray off the maf, or change some plugs...but other than some slow cold starts, not that worried?

 

You could buy a rebuilt head if it turns out to be burnt valves and be good for another 50-75k miles if done and treated properly.

You might need a new AICV or clean your current one.

 

ANything I can think of that would cause a misfire would also throw its own code. eg: TPS, crank sensor

The valve theory might be right one, though I was skeptical of simultaneous valve failure since that would indicate more of a camshaft failure. I'm not sure what a "burnt" valve means. Even 3 cylinders firing correctly should allow you to drive...unless the O2 sensor is catching all that unburnt fuel from the 4th and leaning you out too much. But you operate in open loop from a cold start, so it should still start.

 

If no code, I'll throw in a clogged fuel filter. Sounds like it is having a really hard time getting any fuel at all. Something is preventing fuel from reaching the cylinder all together, or as others have stated something is telling the engine to lean out.

I doubt the loss of compression would cause what you discribe. Just a loss of power with the piston ring, or the dreaded head gasket leak with exhaust in the coolant or water in the oil thing...

 

the truck starts again, bizarrely. the mechanic couldn't replicate the failed start, or the start only with throttle. it drove fine for him, but ran ragged, and the check engine light came on after 15 minutes or so, which threw the misfire code for first cylinder. the leak test has indeed confirmed that the valve on piston 1 is burnt--nice diagnosis, se7enine! not a cheap repair, but cheaper than replacing the engine...he gave a high quote of $3,200, though expects/hopes it to come in lower (includes replacing timing chain, gasket kit, machined valve, etc. plus $90/hr labor). Trying to make up my mind about what to do.

 

Since he will be taking the head off, personally I would expect to service all the valves...and lap the seats ofc. Hope that it solves everything though! (fingers crossed)

 

lap the seats ofc?