dwauckerman

Hi all...need some help. Just bought a 94 toyota 4x4 pickup with 22re 5 speed. Always wanted one. Anyway went for my e-check prior to getting my tags and failed because of high NO levels. Have done some research and the consensus is a problem with the EGR system not keeping combustion temps low enough resulting in high NO emissions. Bought a Haynes repair manual at the local parts store. Checked the EGR valve by applying vacuum to the EGR valve while idling and the engine stumbled badly but did not stall. According to the book the EGR valve passed. I ordered a vacuum modulator from toyota for $50 because the little filter in there was pretty gunked up, however I was still able to blow through it. New EGR valve is 175-200$. Hate to replace it if its not bad. Is the vacuum test reliable for the EGR valve. Does anything else cause high NO levels? Truck seems to run fine. Idles good. Gas mileage is worse than I expected for a four-banger. About 18mpg so far in mixed highway/city with occasional 4x4 use. Also feels underpowered. I just chalked that up to my first truck with a 4 cyclinder. I havent driven many to compare it to. Dont know if its underpowered b/c of engine problem, or its just a dog. I like the truck though. 4X4 works real well. Here are the results of my test:

HC result: 79.7ppm allowed: 194ppm pass
CO result: 0.46% allowed: 2.19% pass
NO result: 1774.4ppm allowed: 1258ppm fail


Thanks in advance for any help,

Dustyn

mr_schuster

sounds like the valve is working ok, but like you said maybe the modulator is keeping it from opening. check your vacuum lines and the routing.

Im not an emissions specialist, but maybe you should check ignition timing maybe to far advanced or something.

One other thing you could try is running high octaine fuel before your emmisions test, it's less flammable.

Someone is gonna bash me for this post I know.

dwauckerman

thanks...I'll recheck the vac. lines and routing...everything looked in order at first glance, and the hoses all appeared to be in good shape... I am also not an emissions expert but being that my HC and CO levels were ok I hate to mess with the timing...I suspect the problem is somewhere in the EGR system, even if its not the valve itself. I have also read that o2 sensor or cat can cause a problem, but most sources point towards EGR being that NO is only value thats elevated.

Thanks for your input,

Dustyn

MMA_Alex

egr is the first thing to check. Check the vacuum line diagrams and make sure they're routed right as stated above. They should be in the fsm, and theres also a diagram sticker under the hood of most of these trucks (underside of hood)

When was the last tuneup? I'd check the plugs (easy to do on the 4-banger), and check the timing. If the timing is too far advanced it can cause excess NOx.

When checking the timing make sure to jump the diagnostic port, and make sure you hear the engine idle down before checking the base timing. If it doesen't idle down check the TPS adjustment.

How many miles? excess carbon build up can also cause high NOx readings...do a search for seafoam if you want to go that route.

Also check the codes by turning the ignition to the on position while the diagnostic port is jumped, and see if you have any codes, specifically any egr codes.

dwauckerman

Alex,

Thanks for the help...this truck has 128k...which I'm sure is enough for some carbon problems. I've never heard of seafoam but I'll check it out. Luckily I do have the vacuum diagram on a sticker under the hood. I'll do a more thorough vac check. Like I said I just bought the truck a few weeks ago. Don't know when the last tune up was. Like you say easy enough on the four-banger, and couldn't hurt the current situation. I've never pulled the codes with a jumper wire before. Sounds easy enough, and I believe it is explained in the repair manual I purchased. I'm very much an amateur. I've never checked/adjusted timing myself, but I'm sure that is explained in the repair manual also. Thanks for the input, this gives me some places to get started while I wait for the dealer to get my vac modulator in.


Just curious...anybody else with a stock 22re? what kind of mileage should I expect on average. Is 18mpg reasonable. Am I off base to think thats a bit low. The 2000 f-150 4x4 I traded for a minivan (if you have a wife and kids your not laughing right now!!! :-) got 15-16mpg all the time with the 5.4 liter, and that thing had guts. Just wondering?


Thanks again Alex,

D

eightnine

i think the average is 19-23mpg depending on how good its running, milage etc..

i got 21mpg on my last tank with a rebuilt 22re and auto

Keith B.

'91, 22RE, 4WD reg cab

MMA_Alex

I just rolled up on 100k with my 22re, and i get 22mpg highway, with 32x11.5 A/T tires, and a manual trans.

To check the code look for the diagnostic port on the inside of the passengers side fender (labeled "diag.", its a little black plastic thing) flip the lid up get a paperclip and put it between the "te1" and the "e1" terminal, and put the trucks ignition on, not started, but on. Same instructions should be on that very same sticker, along with most of the tuneup info.

I'd go ahead and pull one of the plugs, and see how they look, and check the codes, and report back.

to do the timing you need a timing light. you jump the same terminals as above and hook the timing light clip to the #1 wire. point the light at the harmonic balancer (its basically the front end of the crankshaft, outside the engine. theres a little gauge on there that'll tell you how many degrees btdc, and you make adjustments by twisting the distributor (theres a hold down bolt to loosen)

Georgiadave

All good advice above. Your catalytic converter may possibly be bad.

Kiwipushrod

Hey Dustyn,

We have a similar problem (hi NOX) in the hi mileage GM 3.1's, with a low egr flow code.

Problem is always, partially, carbon plugged, intake passage from egr valve, not allowing enough e.g.r. We clean the passage out manually.

I think they use Seafoam around here, try searching seafoam,egr.

I think Your fuel mileage is inline, and better then mine.

Thanks, Kiwi

Targetnut

stumbled badly should mean that it seemed as though it would stall but didn't.

If that is what happened then the valve and passages should be OK. Connect a vacuum gauge to the hose that goes to the EGR and with the engine at operating temperature rev the engine lightly to about 2500 rpm. the vacuum should go up to about 5" to 10". if it does, then the EGR system should be functional If not look at the TVSV, or the EGR solenoid depending on how it is equipped.

If the EGR is working OK then check the timing, make sure the engine is not running hot, check the O2 sensor operation.

dwauckerman

Thanks again for all the helpful advice...according to the manual I have I think the egr valve is functioning...I think the problem is that it is not getting vacuum. I am waiting on a vacuum modulator as I mentioned before. A vacuum gauge would help to check that...however I would have to purchase that. All the vac lines are routed correctly and in good shape...haven't pulled the codes yet...debating on gambling on a can of seafoam...I've read a few threads on it, mostly positive results speckled with a few horror stories...fortunately in OH e-check is free if you fail, so I can try one fix at a time until I pass...you just pay a one-time fee when you pass...will try the modulator first, then basic tune-up (plugs, wires, dist. cap), if no success I'll check timing and TVSV and solenoid. What are the functions of the TVSV and egr solenoid? This e-check is irritating, jsut need to pass...

Dustyn

dwauckerman

Thought I would update in case anyone was curious. I replaced the vacuum modulator on the truck. Bought it from the dealer for $50. Tested again and failed with similar results. Passed for CO and HC improved my NO by about 100, but still failed. Gave the truck a tune-up, new plugs, wires, dist cap and rotor, new pcv and air filter. Truck ran noticeably better...smoother, more power yada yada...still failed for high NO...that was this AM...then I got some bad news...e-check is only free in OH the first three times you fail...$18 per test after that...they tell you this of course after your third failed test...so today I purchased a vac pump/gauge for $50. Tested the vac going to the EGR with the engine hot. When throttle was applied, more than adequate vac was observed, about 12-15" depending on amount of throttle...so I decided to go ahead and pull the EGR and wire brush it and the pipe out well...also check the diag. port for codes and no code were registered...the manual said the check engine light would blink steadily every3-4 seconds for normal...my light was blinking much faster...aprox. every second or maybe a bit faster, but it was steady with no pattern...I am now awaiting the gaskets from toyota to re-install the EGR...I'm at a loss...haven't checked the timing yet, and haven't replaced the cat. Called a local shop I trust for a quote on the cat and they said that the 22re's do have trouble passing the NO portion of OH's e-check. They said a cat will help some. They said I should try it next if the EGR system checks out, which by my estimation it does...anymore suggestions are welcome...I was under the impression the cat was more for CO and HC, does it help with NO also? Well I'm about $180 deep so far on this project. Guess I could still give the old Seafoam a try for $5 I am so glad the government has found another way to waste my money...oh and buy the way, the guys at the e-check (who seem like morons) swear I need a new cat...which makes me not want to get one...

Lost and High on nitrous,

Dustyn

4Crawler

iTrader: (3)

I found retarding my timing 3-5 degrees helped reduce NOx as did really clearing all the EGR passages starting at the exhaust manifold. Run premium fuel for the test and make sure the engine is good and hot before the test. New cat will help a little. I also added a little back pressure to the exhaust (free flowing cat and muffler dropped that too much) with a restrictor plate at the header collector.

dwauckerman

Spent $170 out the door on new cat...NO levels went from 1700ppm to 79ppm!!! Glad I didn't buy a new EGR valve...thanks for everyone's help...I appreciate it...after the tune-up, new air filter, pcv, cleaned out EGR valve and new belts, truck is running much better than when I bought it...also think my mileage is going to be better on this tank...


again thanks to all who answered questions, it was helpful

Dustyn

mr_schuster

Can someone please tell me how a cat is going to reduce NOx.?
I don't really understand.

It seems that NOx is caused by excessively high combustion temps. and reduced by the function of the EGR. The cats funtion is to burn, unburned hydrocarbons not NOx. How will the cat reduce combustion temps?

Glad the truck is fixed though.

Georgiadave

For spark ignition engines, the most commonly used catalytic converter is the three-way converter which converts the three main pollutants of concern — CO, HC, and NOx— to less-toxic substances. The control of NOx involves a reduction process that releases oxygen and the control of CO and HC involves an oxidation process that consumes oxygen. Therefore, a 3-way converter contains two catalyst-coated stages: The first catalyst stage encountered by the exhaust is for reduction of NOx, which produces oxygen employed by the second stage to oxidize CO and HC. 3-way converters work most efficiently with exhaust from engines operated on a stoichiometric air-fuel mixture. Generally, such engines are equipped with closed-loop feedback fuel mixture control employing one or more oxygen (lambda) sensors. While a 3-way catalyst can be used in an open-loop system, NOx reduction efficiency is low. Since NOx emissions are now regulated throughout the world, open-loop fuel systems are obsolete in many jurisdictions. Closed-loop maintenance of the stoichiometric air-fuel ratio is most often attained by means of an engine management system with computer-controlled fuel injection, though early in the deployment of 3-way converters, carburetors equipped for feedback mixture control were used during the transition to fuel injection. Within a narrow ratio band surrounding stoichiometry, conversion of all three pollutants is very complete, sometimes approaching 100%. However, outside of that band, conversion efficiency falls off very rapidly. Two-way (or oxidation) converters act only to control CO and HC, and have therefore been abandoned on conventional spark ignition engines in most jurisdictions due to an inability to control NOx.

mr_schuster

interesting...

Targetnut

That is an excellent description of catalyst function!