hello from california

1993 ford e250 5.8 sportsmobile camper
previous owner put 32" tires on it.

I got a really good deal on this van because it wouldnt smog.

a shop already replaced an exhaust manifold, egr valve and tube, tps and o2 sensor (bosch oe).

It had codes 334 and 172 when i bought it, lean exhaust and egr open at idle.

all the cylinders test 135-145 psi cold compression after sitting for a few days.

I found someone put plugs in it that were gapped to .055 instead of .044. the plugs were all white and fouled.

I gave it an ECT sensor and EVP sensor and plugs, wires, cap and rotor and the codes are gone.

it has good fuel pressure and base timing.
new plugs arent fouled yet.
seems to idle well with an occasional shake. sounds healthy. doesnt have much power, doesnt want to accelerate.


It is now getting about 12.5 mpg over 100 miles of mixed driving and is still a gross polluter in HC and CO..

I am thinking this could be a bad cat or bad smog pump?
It idles well but doesnt want to accelerate. I dont hear the cat rattling or smell anything in the exhaust though.
the smog pump knocks sometimes.

the fact that it seems to have a good AFR and get good mpg but is still a gross polluter makes me think its the cat.
any thoughts?

 

Are the air injection divert and bypass valves working correctly?
Is the crossover pipe at the back of the heads intact?
Are the check valves in the air injection system working?
I redid my entire air injection system. The bypass/divert valves can be almost impossible to get to. Do you have a dog box inside that gives you engine access?
My truck is an '88 F150, 5.0.
I have separate bypass and diverter valves. The bypass valve was stuck. I freed it up by removing it from the engine bay and soaking it in WD 40.
I removed the hose feeding into the diverter valve, at the back of the engine and when the engine was running, I could feel the pulse of the exhaust, because the check valve had failed.
My diverter valve was rusted through.
With the diverter valves, bypass valves and EGR valve, if you apply pulmonary vacuum, they should open, then spring closed without vacuum.
I blew air through the diverter and bypass valves with a cordless leaf blower to simulate the air pump and kept applying vacuum until they worked, after soaking them with WD 40.
The tubing from the diverter valve to the catalytic converter and the check valves can be purchased new. I bought a used diverter valve from a forum member.
Instead of trying to unthread the check valve from the crossover pipe at the back of the engine, I added one just before the diverter valve.

My divert valve. Yours might be a combination divert/bypass.


Tubing from my divert valve to my cat. This is looking up from the cat. You can see the check valves and curved hose going to the cross over pipe at the top of the picture.

On a cold start, for about 90 seconds, air should bypass out of the system.
At about 90 seconds, air should go into the heads.
When the computer is satisfied with engine temperature, air should go to the cat.
On decel with no throttle air shouldn't go to the cat.




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thanks a lot for the info.
was yours throwing any codes? did it have trouble accelerating? what were your symptoms?

Mitch

 

My truck was a project. I decided to put everything back to stock or as close as possible.
My truck was registered "historic" in Maryland, meaning the previous owner had abandoned or modified almost everything.
There is no emissions testing in Md for vehicles of this age but all the components have to be "present".
I figured why not make them operational.
I also replaced all the vacuum lines with 5/32" rubber hose.
My SPOUT connector was laying in the driver's door pocket, so my computer wasn't in closed loop. In Maryland most historic registration vehicles are not up to mechanical standards, either because the owners can't afford to repair them, or they just don't want to.
Since I've never dealt with emissions testing with this truck, I can't give much advice on the specific readings.

 

sounds good. thank you for the info on the AIR system I will have to look into it.

Mitch

 

I have one more question for ya

I am getting ready to test my AIR system in order to eliminate it as a factor.

basically if i unplug the hose going to the exhaust from the smog system with a warm engine I should get a constant flow of air from that tube is that correct?
as the smog pump should be constantly sending air into the exhaust at idle once the engine is warm?

I am growing more and more convinced I have a bad and partially clogged primary cat. it would explain why the engine doesnt like to pull on the highway and the smog numbers are so much worse at 25mph than at 15..

can anyone else weigh in?

Mitch

 

Yes, if the engine is up to operating temperature, the air should be pumping to the cat.
And yes to others weighing in who have emissions testing experience.

 

air system works. it buzzes like a bee and doesnt blow much at idle but when you rev the engine the air pressure increases substantially. i disconnected rubber hose at the back of the engine that goes to a hard line down to the cat. there is a valve in the hard line that i dont know how to test, its very clean.
edit: i didnt disconnect the line in the exhaust because its raining here and i dont feel like getting under it right now.
I did observe the air system redirect from the heads into the exhaust after starting the engine

as far as the cats being clogged I dont get much temperature difference between the front and rear of the first cat, and the manifolds are both roughly the same temperature. the exhaust doesnt really smell either..

I pulled a couple plugs again. they only have about 100 miles on them. still look brand new. no discoloration or deposits. the electrodes are very slightly orange-brownish from heat.

I am totally stumped why this thing has no codes, sounds like it runs ok but has no power and is a gross polluter. all i can think is its supposed to feel slow and has bad cats.

Mitch

 

The buzzing is normal.
The divert from heads to exhaust sounds normal.
The valve in the hard line is probably a check valve. It's function is to only allow air flow one way, so hot exhaust doesn't back up into the divert valve. Sounds like the divert valve is working so the check valve is probably ok.
Does the exhaust system look old? Maybe the cats aren't functioning correctly.
Someone more experienced with emissions troubleshooting will have to chime in.

 

I agree that the smog system seems to be working properly. the cats are original from 1993, with all the abuse this van has seen it would make sense that they are non functional or partially clogged. the van does only have 95k miles though

I am going to try and back pressue test the exhaust at the o2 sens port to confirm a partial clog. ultimately It seems like the issue could be bad cats + something else.

thanks for your help regarding the secondary air system

Mitch