Yamalol

1986 SR5 Xtra Cab, 22re.

Truck is new to me and failed Washington, DC emissions. When I got the truck, TPS was disconnected and it had been straight-piped. I installed an EPA (but not CARB) compliant catalytic converter, set the timing per the manual, and went through emissions.
HC Tested: 225ppm, limit 220. FAIL
CO Idle reading: 3.18%, limit 1.20%. FAIL
Next, I replaced the TPS with an OEM Denso unit, adjusted it per the manual, and replaced the o2 sensor with an OEM sensor, both purchased from 22RE performance. I set the timing per the manual again and went through emissions again.
HC Tested: 154, limit 220. PASS
CO Idle reading: 2.40%, limit 1.20%. FAIL.

I'll note that the truck runs great. Idles smoothly, and revs out find. Idles low when I first fire it up, but other than that, no driveability issues.

I have to pass by October 2, or else I'll kinda be out of luck. I have a couple of thoughts:

1: The truck has headers on it. I think that's the biggest issue, and I don't mind buying a stock manifold/headers, I just can't seem to find the hard line that connects to the manifold. My understanding that the purpose of the line is to supply fresh air to the exhaust. I could be wrong, I can't find mention of it in the manual.
2: I also don't mind buying a CARB compliant cat, I just don't want to spend the money if it won't help the issue. My understanding is that a better cat won't do a whole lot for CO emissions, but I could be wrong.
3: I haven't touched the ECT sensor, or the MAP sensor yet. I have a replacement ECT sensor (Autozone part, not OEM), but haven't tested either.
4: I have the timing set at 5 BTDC on the nose with the test port jumped. Goes up to around 12 with the jumper removed. I could drop it more, but I can't see that fixing the CO issue completely, but I could be wrong.
5: DC is pretty lax on their visual inspection. I COULD try popping a hole somewhere in the exhaust pipe. However, given that the CO reading is a percentage, I'm not sure if that would lower the percentage since no fresh air would be getting in.
6: On tap for today is an oil change, and fresh spark plugs.

Let me know what you think... PLEASE. hahaha. Thanks.

scope103

This article may help: http://www.cygnusx1.net/Media/Supra/...taTech/h56.pdf The basic cause of high CO is running rich. You can't adjust mixture directly, but one of the (many) causes listed in that article is excessive fuel pressure at the injectors. Fuel pressure isn't that hard to check; you might consider that.

Usually, "too rich" is caught by the O2 sensor, so checking its operation is worthwhile (and easy). https://web.archive.org/web/20150306...42oxygense.pdf Look for the voltage on Vf fluctuating at least 6 times in 10 seconds.

The tricky one is a leaky injector. You'll have one rich cylinder and the others okay. The O2 sensor is trying to get the exhaust stream right, so it leans out the mixture on all cylinders; one running a little too rich, and the rest running lean.

Good luck!

Yamalol

Thanks for the info! I’ll add that I just did spark plugs and they all looked the same. Maybe a tiny bit of carbon, but nothing crazy.

The fuel pressure point is interesting. Going to look into a failed regulator first.

edit: FPR appears to be working.

Dernation

I love my 86 22re sr5 ext 4x4!. In answer to number 1 though, the 86 only has 1 connection to the exhaust, the simple egr valve. It never got the "pair" system with the resonator built into intake. Good luck!

Jimkola

The cat won't make much of a difference, if any. I ran a straight pipe for awhile, and even had a smog test with it (sorta looks legit) and my numbers didn't suffer with it.
Scope gives great advice regarding this issue. My only additional thoughts would be sparkplugs, use NGK or Denso regular resistor plugs. Bosch, Champion, etc I would definitely pull.
I always put Chevron super unleaded in mine a few days before the test.
I get the system hot before I drive in. Few miles down the freeway. Try not let it sit and cool down.
The 22R# runs cleaner at the idle test if its at the higher end of the allowed rpm range. I've watched it during a manual test, and you can see the numbers drop significantly, and suddenly, as the rpms increase. My Suzuki Samurai was the same way. Fortunately, the gentleman who does my tests has a vehicle like ours and understands its idiosyncrasies
If you get time, find the method here for setting TPS with a timing light. Far more accurate than the FSM. I doubt it would help with your current issue. Just a good method to know about.

Yamalol

Thanks. There isn’t really an idle speed limit in DC, although I imagine if I pull up to the test center with the engine screaming they might not accept it. I’ll pump it up for the next test. Plugs are NGK.

I think the important takeaway is that I’m essentially running a bit rich and there are only so many reasons why that could be. I tested the AFM and it seems to be working. I bench tested a new coolant temp sensor, will swap that in today then bench test the old one. I appreciate you folks for chiming in!

I’m also tempted to buy a AFR gauge so I can see how I’m running in real time and no have to go by smell, they’re just kinda pricey…

Jimkola

Too much fuel, or not enough air. Excessive fuel would seem the more likely culprit

JoeS

Is the EGR valve working properly? Read when the EGR valve fails, it can cause an increase in Nitrogen oxides (NOx), hydrocarbons (HC), or both. Easy check to eliminate a potential cause. I'm in SE VA and we do not have emission testing as part of the State inspections like you in NoVA...............yet.

scope103

Yamalol failed on CO, not NOx. The EGR valve critically affects NOx, but should have little impact on CO.

While we're at it, what are the units for your HC? In California, we use ppm, and the maximum allowable (for my vehicle and year) is 40ppm at 25mph. 220 could be mg/M³, but even that sounds awfully high. Did you get a CO2 percentage? The article I cited states that is a good indication of combustion efficiency. You want high 14s or low 15s.

Yamalol

I just pulled the upper intake manifold to pull the injectors. Sending those to 22re Performance for a rebuild. There was some oil sitting in the bottom of the manifold, going to clean that up and replace the PCV valve and grommet. The PCV valve is loose in the grommet. I also ordered spark plugs from 22re Performance. I noticed a few things while pulling the manifold. The egr pipe was loose. I also noticed a sizable crack in one of the hoses (not pcv hose) going from the top of the valve cover to the intake manifold. Going to replace that too.

Scope, to answer your questions, in the most recent test (which was a pass for HC in Washington, DC) I had 154ppm (limit is 220ppm). DC does a 2 speed test, one at idle and one at high idle of 2500 rpm. The printout I get only shows one number, so i have to assume it is an average, maybe with a bias towards idle or 2500rpm. Note that there is no testing under load. Both tests are just a tester in the tailpipe for about a minute at both engine speeds. My CO2 reading was 11.28%.

Complete test results:

First test
HC: 225 ppm, limit 220ppm - FAIL
CO: 3.18%, limit 1.20% - FAIL
CO2: 12.17% (No limit)

Second test
HC: 154 ppm, limit 220ppm - PASS
CO: 2.40%, limit 1.20% - FAIL
CO2: 11.28% (No Limit)

JoeS

I'd still check it. It's an easy fix if it is bad or stuck open from carbon build up. It may not be much, but if it has some any impact it's worth a look.Especially if it's original on a 37 year old truck. It might not take much to lower he CO, so it passes. Nothing loss by checking. "The EGR system significantly reduces the amount of NOx, but if too much exhaust gases are introduced into the intake, it can have an impact on the increase in emissions of carbon monoxide (CO), hydrocarbons (HC) and particulate matter (PM). "https://x-engineer.org/exhaust-gas-recirculation-egr-introduction.

Yamalol

I think the fact that the hard line to the intake manifold was loose means a significant amount of unmetered air was getting in. could be a big part of the problem.

I ended up pulling the valve cover this afternoon. Chain and guides look good. Also did a valve adjustment, and replaced the PCV grommet.

scope103

Yeah, the CO, CO2 and HC all point to running really rich. For my part of California, the limit for CO is 0.59% (average passing number is 0.04%). The average passing number for HC is 17ppm. My 30-yr old truck (with 0.3M miles and the original Catalytic Converter) clears those numbers every 2 years without difficulty. You should be able to as well.

Good luck!

Yamalol

I passed emissions this morning! Thank you all for the advice. I think in my case, the main issue was a vacuum leak at the EGR tube. I'm a little annoyed that I didn't catch that sooner. I'm sure replacing and adjusting the TPS, and replacing the o2 sensor helped too, as did everything else in smaller parts.

Jimkola

Woot!

Blueman

I'm with Jimkola on this. Have your tank filled with mostly fresh gas the day before (or nearly) the test, and splurge on the fancy fuel. Having the tank nearly full will help on the evap test -- ask me how I know.
But the biggest thing, find a smog shop who's old-vehicle-friendly, and willing to take the time to help it pass.

For reference, here are the latest numbers I see for my '87 22RE EFI with about 200k miles:

Blueman

I've had old hard leaky vacuum hoses before cause an issue -- I, and I'm sure many others, went through and replaced them all proactively.

Glad you found success!

Yamalol

Unfortunately in DC there’s only one centrally-located emissions testing center run by the city government. 8 bays with a steady stream of vehicles all day. If you fail, they give you your report and send you on your way. Oh well!