Hello

So the car is failing it’s smog pretest. 2500rpm is passing fine but when she is dropped down to 750 HC climbs threw the roof. 1300-1500 HC at 750rpm and 100 is the limit. Engine is new probably around 100 miles and several hours of run time.



Things I have personally replaced or checked:

New fuel pump, new fuel filter, new pressure regulator, new pulse damper, new fuel temp sensor. O2 sensor operation verified, MAP sensor verified, TPS verified. Both CATs installed and working.



Things I have not checked yet:

Secondary air injection system, next on my list to check. The pump comes on and goes off when supposed to but as far as it pumping air and that air going where it needs to go not verified yet. I have not check IAT yet.

 

air injection needs to go to port air, and is probably a good next place to check.

 

Are you testing the car hot or cold? Make sure it's good and hot when you test it. Air injection also definitely needed. Make sure it's up to spec.

 

Testing the car warm, she ran for like 15-20 min before I drove her over and it’s a 10 min drive there never shut Her off. Idol is just to rich you can smell it if you walk to the back of the car that unburnt fuel/rich exhaust smell. Plus 1300-1500 HC at idol and only 30-40 at 2500rmp.

I pull the air injection controller tonight and put a vacuum checked it was working correctly which it was. I also OHM checked the solenoids and they where within limits as well. I then pulled the air pump off the car and put it in the vice and spun it with the nut and an electiric drill and it pumped air. I didn’t get it much revs cuz I know it shuts off at like 3k rpm. It was pushing air ok I mean spec says like .7 psi at idol that’s not much. It was making a lot of noise so I put a very small amount of pneumatic oil in it like 1/4 to a half of a soda bottle cap for comparison.

any other idea why she would be getting to much fuel at idol? Fuel Line pressure is good and line pressure hold test is good.

 

What about throttle body? I noticed the arm with the screw in it that the wax rod is supposed to push on does not move freely. With engine cold here is a large gap between that screw and the wax rod part. I’ll try to upload a picture.

 

 

My O2 sensor would go in and out of spec. The TPS can do that as well. I replaced both. (We don't have smog test in BC.)

Have you looked inside your ecu. Its 25 years old, eh?

Filter for MAP sensor is sometimes put in in the wrong direction.

Leaking injectors?

Is the little plunger valve in the air control valve working. (Careful it may fall out when you inspect.)

 

Replace the 02 sensor before you even think of going near a smog shop.

 

Can't hurt to replace the O2 sensor as Natey mentioned. Rotary Performance | FD Engine Maintenance
I'm going to assume the stock cat is in the car. Double check that the air pump air hose is attached to the cat as well.

 

I believe there is a check valve in the line to the cat. Maybe check the check valve as well.

You mentioned the fuel pressure regulator. It needs vacuum to be on for it to remain open, if I recall correctly.

So it might appear to work when you check it, but there might be an issue with the vacuum when it is installed.

 

Fuel pressure regulator is good. I did all the pressure checks and it’s in limits down about 5psi from the old one.
Car has been the same with both my O2 sensors first time I took it in I had my downpipe on not my pre cat now it has pre cat on it. I bench checked both O2 and they work fine.

need to check the check valve down by the cat just gotta get the car up in the air to get under there. I know it’s all hooked up cuz I put the hole drive train in myslef and have had the motor out once to swap all the intake manifolds. I’ve double and triple checked all my vacuum lines and connections everything is good.

The air pump seemed fine to me, was pumping air fine. And checked the control valve the pump goes to and both valves work correctly and all 3 solenoids checked good.

About to go pull the throttle body off and get that arm broke free and working as it should. Only thing holding it on atm is the coolant hoses.

not going to beat on the motor cuz she’s not fully broke in yet less then 300 miles and only a couple hours run time past that.

and thank you for the input keep it coming.

 

So the arm on the throttle body that was not moving was the one with the fast idol cam. It was stuck open or way away from the wax pellet thing. Worked on it got it all broke free and function properly did not touch any adjustments just got the arm swinging freely.

don’t see how this would affect my rich idol problem from my understand it just pumps the rpm so the motor can heat up faster during cold start. Correct me if I’m wrong.

 

Injectors, leaking?



This thread is running concurrently. May be a clue.

Fuel leaks thru Exhaust Mani Gasket when engine floods?

 

Injectors are not leaking she held pressure fine on the leak down test.

How about TPS out of adjustment? Those HC have to come down quite a bit at idol.

 

Definitely check TPS voltage. Both ranges.
Check the clutch switch is sending a signal to the ecu. It does affect the idle. Same for the trans neutral switch if they are just shifting to neutral and letting it slow that way.
Adjust the throttle dashpot in case the high HC is happening as the throttle slams shut.
Plug the purge solenoid to intake hose. It may be getting extra fuel that way. A check valve accidentally installed backwards would act the same way.

 

Thank you for input I will double check my check valves and purge valves as well as taking a look at the neutral switch. I readjusted my TPS back to it’s marked location when I put it back on after getting the arm broke free I will verify voltages when I get everything out back together just wanna check all those valves and stuff first.

the dash pot may not be working 100% but it’s a none issue on the test cuz we are slowly releasing the rod holding the pedal down for the 2500 rpm. She is golden at the 2500rpm slowly pull the rod letting her roll back down to idol right as she gets to idol HC starts to climb and just goes WAY over the limit.

 

TPS can test within spec, then go out of spec when engine is hot.

Borrow a friends and see if it helps.

Is it 25 years old?

 

TPS doesn’t look that old.

BUT! I did start looking at all my check valves thanks to RXSpeed16 and low and behold I found a vacuum check valve installed backwards. And it just so happens the be the vacuum that goes that goes to the air control valve. So that valve would not have been getting any vacuum to open it. It’s the air injection valve for port air that would not have been opening so I wasn’t getting any air injection into port air before with that check valve backwards.

The arm on the throttle body is now working correctly. When I started her cold idol was faster then cold starts before once she got up to temp idoled much better. Also now with the check valve installed correctly idol is smoother and you do not get that rich exhaust smell when you walk to the back of the car just that normal rotary exhaust smell.

I will post again after the next test let y’all know how it goes.

 

that would do it, it will never pass any emissions check without port air...

oh and Idle is when the engine is at zero throttle and 750rpm, Idol is one of these things,

 

Which ones the Idol?

 

Now she is throwing a code 16 EGR function sensor. I had already repaired the wires on it they are still good. I think the problem is it was letting vacuum bleed out the sensor. I tried tightening it but it’s all plastic and started to break cuz it’s old and brutal from being cooked. So I just globed a bunch of gray RTV on it and slapped it back together. I’ll test it tomorrow for function and with a meter to make sure it’s good before I put it back on. Oh the gasket was also only cut for one hole so it would have failed function test if they had tested it. Gotta cut a new gasket anyway cuz it broke into pieces pulling it off so I will cut both holes and make functional.

 

Engine Bay "Whack a Mole".

Check with your banker before proceeding further.

 

the EGR valve should hold vacuum, but it is not big enough to effect (or affect?) the idle. in fact the EGR may not even turn on during the emissions test. you do need to make sure the Check Engine Light stays off though.

 

Best way I know to solve this problem is to move to TENNESSEE
Antique vehicle registration for 25 year old cars
$35 one time fee
No emission test

 

so turning a check valve around is harder than moving across country? :P