Random/Multiple Cylinder Misfire on 1998 Taco

[zlathim]

My friend just purchased a 98 Taco with the 2.7 litre four banger.

He is having some trouble with it and asked me to help. He is going to bring it over for me to look at later today. He has pulled the codes with his ODB2 scanner. Here are the codes:

P0300 Random/Multiple Cylinder Misfire
P0301 cyl #1 misfire
P0302 cyl #2 misfire
P1300 Igniter Circuit Malfunction No. 1
P1310 Igniter Circuit Malfunction No. 2

The engine runs very rough. He said that he thought that there were two plug wires switched (based on a haynes manual he was browsing at Vatozone), and he said he switched them around. It had no effect on how the engine runs. Sounds unlikely to me unless both of those cylinders are dead ( I am assuming #1 & #2 based on the codes, but I forgot to ask which plug wires he switched). Like I said before, I haven't seen the truck or heard it run yet.

Can anyone point me in the right direction? I haven't seen the vehicle yet, so like I said, I'm just trying to get the right train of thought going here. Any help would be much appreciated.

[zlathim]

Does anyone have any insight?

[The Phoenix]

How many miles? Wires could be bad.

[zlathim]

I worked on the pickup last night for a little while as I got a late start. It has approx 120K on it. The NGK plugs looked fine, i.e. light tan insulator and electrode area. #1 was a little darker, but definately not fouled.
Here's the compression test results:

Cyl# 1= 50 psi
Cyl#2= 145 psi
Cyl#3= 150 psi
Cyl#4= 157 psi

A quick and dirt cylinder leakdown test showed no bubbles in the coolant or hissing from the dipstick tube on the engine. I'm really not sure that I was using the right TDC mark... It was getting late and I was tired. I am going to pull the VC today when I get home from work and make sure both sets of valves are closed.
Can anyone give me an idea of what I'm looking at if I end up adjusting the valve lash? Is this one of those motors with replaceable shims for setting valve lash?

Any help would be appreciated, However please don't respond by saying that I should replace all plugs, wires, etc, etc. I can and will test everything in part, but I am not interested in throwing a bunch of money at this thing only to find out it still has a miss.

[zlathim]

bump to the top

[mustang67408]

Originally Posted by zlathim

I worked on the pickup last night for a little while as I got a late start. It has approx 120K on it. The NGK plugs looked fine, i.e. light tan insulator and electrode area. #1 was a little darker, but definately not fouled.
Here's the compression test results:

Cyl# 1= 50 psi
Cyl#2= 145 psi
Cyl#3= 150 psi
Cyl#4= 157 psi

A quick and dirt cylinder leakdown test showed no bubbles in the coolant or hissing from the dipstick tube on the engine. I'm really not sure that I was using the right TDC mark... It was getting late and I was tired. I am going to pull the VC today when I get home from work and make sure both sets of valves are closed.
Can anyone give me an idea of what I'm looking at if I end up adjusting the valve lash? Is this one of those motors with replaceable shims for setting valve lash?

Any help would be appreciated, However please don't respond by saying that I should replace all plugs, wires, etc, etc. I can and will test everything in part, but I am not interested in throwing a bunch of money at this thing only to find out it still has a miss.

You probably have a burnt exh valve. Attach the leakdown tester and listen for hissing thru the muffler. It's a common (I use this term loosly, we have done several over the last few years)(nothing cronic) thing for this 4 cyl engine. Adjusting the valves usually will not help, especially with the compression that low in cylinder 1.

[zlathim]

Thanks for the reply Mustang.

I need to redo the leakdown test, as I'm just not confident I had it on the right TDC mark.

So if I determine it to indeed be leaking from the exhaust side, I should not attemp to adjust lash, but simply prepare to pull the head and do valve work? Should I be prepared to have a new seat installed, or is it possible to just install a new exhaust valve?

[mustang67408]

Originally Posted by zlathim

Thanks for the reply Mustang.

I need to redo the leakdown test, as I'm just not confident I had it on the right TDC mark.

So if I determine it to indeed be leaking from the exhaust side, I should not attemp to adjust lash, but simply prepare to pull the head and do valve work? Should I be prepared to have a new seat installed, or is it possible to just install a new exhaust valve?

IF, it is leaking thru the exhaust, then just pull the head and replace all the EXH valves. The seats are usually just fine. We usually do not send the new valves out to be installed, but install and seat them ourselves with some FINE LAPPING compound, then adjust them and re-install the head.

[zlathim]

Mustang- Fantastic information. Thank you.

Are the valves adjusted via shims?

[mustang67408]

Originally Posted by zlathim

Mustang- Fantastic information. Thank you.

Are the valves adjusted via shims?

YES, they use shims
Here is a PDF on how to inspect the clearance.

[zlathim]

Most excellent! Thank you very much!!!

[zlathim]

Mustang-

I performed the Leakdown test correctly last night and it is indeed leaking from the exhaust valve/s on cylinder #1. I am going to tackle this thing myself, but I have a few questions:

Can I get the FINE LAPPING compound at NAPA or Autozone? Is there any particular brand you prefer?

It looks like I may be able to rig substitutes for the two SST's listed as needed for shim replacement. Do you recommend that or should I bite the bullet and buy the SSTs? Do you know how much they are?

I am planning on using a spring compressor designed to use while the head is attached to the block. I am wondering about the clearance around the spring and whether I will need to get something different. Is there anything special about the ones you use?

Is it easiest to just remove the exhaust camshaft from the head in order to replace the springs, or is that a no-no for some reason?

It looks like I can simply remove tension from TC and then remove the upper sprocket from the camshaft. Then just keep the chain from falling down with some wire or something. Does this sound about right to you? Sorry to be a PITA, but I want to try to get it done over the weekend and I want to be prepared.

What does the book say for flat rate? I know that I will never meet it, but I'm wondering how long a dealership guy takes to do it.

[mustang67408]

Originally Posted by zlathim

Mustang-

I performed the Leakdown test correctly last night and it is indeed leaking from the exhaust valve/s on cylinder #1. I am going to tackle this thing myself, but I have a few questions:

Can I get the FINE LAPPING compound at NAPA or Autozone? Is there any particular brand you prefer? Yes, they should carry it. I use whatever the parts dept can get.

It looks like I may be able to rig substitutes for the two SST's listed as needed for shim replacement. Do you recommend that or should I bite the bullet and buy the SSTs? Do you know how much they are? With the head off , it is just as easy to reinstall the cams, measure the valve clearance and adjust from there. No SST's needed. They are expensive and usually take 4-5 weeks to order. They are only for cylinder heads "ON" the vehicle, yours will be off replacing the valves, just measure the clearance before you remove it. Then measure again after you replace the valves.

I am planning on using a spring compressor designed to use while the head is attached to the block. I am wondering about the clearance around the spring and whether I will need to get something different. Is there anything special about the ones you use? We use ones that look like a big "C" with an attachment for getting down around the small valve spring. Most auto parts stores have this stuff, nothing really special.

Is it easiest to just remove the exhaust camshaft from the head in order to replace the springs, or is that a no-no for some reason? You have to remove the exh cams to get the springs out to remove the exh valves to replace them. Take the head off, it is so much easier that way, that tring to do it with the head on.

It looks like I can simply remove tension from TC and then remove the upper sprocket from the camshaft. Then just keep the chain from falling down with some wire or something. Does this sound about right to you? Sorry to be a PITA, but I want to try to get it done over the weekend and I want to be prepared. Yes, it can be done this way.

What does the book say for flat rate? I know that I will never meet it, but I'm wondering how long a dealership guy takes to do it.

I could do this in about 4-6 hrs with all the parts in front of me. The book pays 20 to overhaul the cylinder head, which includes stripping for resurfacing and replacing ALL valves and valve guides. You guides should be fine , unless you find a broken one (I doubt it).
Do not rush and take your time.
PM sent

[zlathim]

Fantastic information Mustang! I certainly appreciate the help. I got your PM and sent you an e-mail.

This site rocks!!