My 96 camry 2.2 federal with auto at 307k miles is running -25 rich long term with short term at stoichiometry. Revving to 2500 rpm makes the long term better -17.
My question is what all could cause this.
I've already tried all new sensors, thermostat, air filter, purge valve, fuel pressure regulator, and fuel injector cleaner guy said the injectors are not leaking down
You don't think a rebuilt cylinder head will stop it from running rich? Thanks for your help
As I explained, it doesn't sound like it's running rich, just burning oil.
No. Heads won't fix worn piston rings. Changing the valve seals might help a little bit, if they're worn out. But I would question the financial wisdom of pumping money into a 27yo car and engine that's already this tired.
Fsm compression spec is 178 but 142 min . My results were...
1. 130
2.147
3. 135
4. 175
Not only is compression low, but it's inconsistent across cylinders. Cylinder 1 holds less 75% less pressure than cylinder 4.
I came here looking for a repair fix,
As we explained , your results indicate a worn out engine. There is no fix other than a new engine. But you made it to 300k for which you should be thrilled. Congratulations!
because egr valve was never mentioned
your egr valve is inconsequential to poor compression. Even if there are other problems (worn out timing chain/belt, exhaust leaks which might cause lean O2 readings, etc.), it's financially unwise to pursue any major repairs at this point.
There is no maf just a map. And I did clean the throttle body, but that did not help. the fuel pressure is in spec too
is the MAP sensor reading correctly? Does it go to zero at WOT? Does it go hard negative when you snap the throttle shut?
Is the IAT sensor reading correctly?
I did clean the throttle body,
did you peek at the valves to see if they're dirty?
Yes, the scanner shows atmospheric pressure at wot. All of the sensors are reading correctly, I changed them to new sensors and am still getting the same readings.
I did not look at the valves, but the compression test may point there 130 147 135 175 ( min 140, max 178)
Is it misfiring? Did you examine the spark plugs tips, and visually confirm good spark?
No misfires, new spark plugs. Verified good spark
hmm not much left. even if the injectors aren't leaking down, they could still be gummy and operating stiffly. The only thing I can think of would be malfunctioning PCM, or ...
is it ACTUALLY running that rich? Is your tailpipe sooty. Does the exhaust smell like gas? Maybe the O2 sensors (or the wiring harness for that matter) are faulty and misreporting. Did you check the data?
- Ecm has 1500 miles on it.
- It's really running rich , mpg is down, soot in exhaust but no gas smell , I have hard time breathing sometimes though
- Drove it richer with propane
- Cat converter vacuum test seemed to pass
so I would check the valves using a boroscope, and I would perform an injector balance test.
That's all I've got.
{black}:idontknow:
That's all it can be?
I did notice the intake manifold vacuum gauge changed from 21.5 inhg steady to 19.5-20 inhg (vibration fast ) when it started running rich
Also noticed rust buildup on both camshafts on every lobe (the full lobe)
That's all it can be?
that's all I came up with
did notice the intake manifold vacuum gauge changed from 21.5 inhg steady to 19.5-20 inhg
pretty tiny change. You can try cleaning/replacing the IAC valve. Anyway this shouldn't affect performance at 2500 rpm.
rust buildup on both camshafts
are you sure it's rust and not varnish? If that's true then you have moisture in the engine. Not good.
Does the car sit for long periods of time, or do you only drive short trips not letting it get up to temp?
Hopefully it's not a blown head gasket.
I think it's rust. Car sat for 2 years, that's when it happened, until I started driving it daily again. Seems to maintain coolant level.
Thanks for your help. I have photo of cams but can't seem to see how to upload
Car sat for 2 years
I bet your problems were caused by this.
injectors would be my top suspects
Even if you park a car, you need to start it up and run it until hot once in a while. Otherwise you get rusty engine parts.
can't seem to see how to upload
Main page > "READ THIS FIRST - Forum Guide"
It's post number 15 in this thread
During the two years the car sat , I started it up every 2-3 months and let it run for 30 minutes.
I'm currently Reading about how to do an injector balance test. I have a cheap obd2 basic laptop scanner with fuel trim data and a fuel pressure gauge I can hook up at the fuel filter.
I just reread the email from the injector guy. It states the injectors have a flow balance of 2.6 percent (38-39 cc)
During the two years the car sat , I started it up every 2-3 months and let it run for 30 minutes.
well if the engine ran, then that means the critical areas of the cams have been polished. The rest I wouldn't worry about.
I have a cheap obd2 basic laptop scanner
that probably won't do it
It's post number 15 in this thread
well nobody is going to go digging for you, so I'll post the photos here for you, so we can all benefit from it
that brown stuff is varnish, like I said. And it's baked on there pretty well. This engine has been poorly maintained in the past, or run low on oil, or it could just be from having 300k on it. You could try some oil system treatments to help loosen up that grunge, but no guarantee it'll fix your problem. ( https://carkiller.com/scottykilmer/qa/ats-505-cro-oil-treatment-result-review-2/)
It's possible the engine has just had it. Have you tried a compression test?
Yes the psi compression results were
130, 147,135,175
(fsm specs min 142 max 178) ,
For wet compression numbers add 90 to each cylinder
those are not good numbers. Is it burning a lot of oil?
I checked last summer. It burns 1/2 quart In 1500 miles
That's a fair bit of oil, and might explain the soot. Burning oil also gives bad oxygen sensor readings.
I would just try the oil system treatment, and baby the engine until it gives up.
You don't think a rebuilt cylinder head will stop it from running rich? Thanks for your help
Yes the psi compression results were
130, 147,135,175
(fsm specs min 142 max 178) ,
For wet compression numbers add 90 to each cylinder
As @imperator noted, these numbers are low = worn engine.
You don't think a rebuilt cylinder head will stop it from running rich?
Well yes, a rebuilt cylinder head might provide better fuel to air ratios. Still, that's an old vehicle with 300k miles, if you provide the labor you buy a 'good' cylinder head, you'll spend $500 more on top of what you've already spent. You will still have an older engine with low compression. May not be such a wise decision IMO
Can the -25 % rich long term fuel trim at operating temp idle (-10% when cruising at 60 mph) be caused by the piston rings solely or is there another reason for the large negative fuel trim.
Fsm compression spec is 178 but 142 min . My results were on a cold engine with all spark plugs removed and throttle plate fully open.
1. 130
2.147
3. 135
4. 175
When I done the wet test I added 4 tablespoons oil to each cylinder and each cylinder went up by 90 psi
Can the -25 % rich long term fuel trim at operating temp idle (-10% when cruising at 60 mph) be caused by the piston rings solely or is there another reason for the large negative fuel trim.
This has been going on since July of 2023 and the things that can cause negative fuel trims have already been discussed in this thread. You can also search youtube and other internet sources for more information.
When I done the wet test I added 4 tablespoons oil to each cylinder and each cylinder went up by 90 psi
Your piston rings and/or cylinders are worn. At this point that car is getting within spitting distance of 30 years old with with very high mileage. It is just not worth putting a lot of money into that thing. (I drive a car of similar age and even higher mileage and while it is currently running well if it developed expensive problems I would not hesitate to move on to something else.)
I have searched the net and watched videos. I came back to this thread to ask specific questions in a certain way, but all I get is it's not worth the money. I'm looking for a solution to keep driving this specific car (hence, I came to a car repair website). The specific way I asked is for example, I said I took out all spark plugs to test compression on a cold engine. Google says that all plugs being out will cause lower compression, as will testing on a cold engine. I also said I added 4 tablespoons oil to each cylinder. Google says a few teaspoons is plenty and the more will raise compression. I'm assuming this would put the compression at the minimum. The wet test would still say rings are worn. Google also says such a large negative long term fuel trim is likely caused by something other than low compression. However, google is unreliable because it will also tell you the opposite of what it had told me before depending on how I word the question. Do you just sound snippy or is it just me
I apologize. But seriously, I came here looking for a repair fix, not to stop working on the car. And all the potential causes were not discussed, because egr valve was never mentioned
I came here looking for a repair fix, not to stop working on the car.
You received several suggestions in this thread for areas to troubleshoot. We have no access to members' cars and can only make suggestions of areas that may need attention. There are many variables. Only if something is very obvious can we say what the actual part or parts requiring replacement might be. (If you lived near one of Scotty's locations he would likely be happy perform an in-depth, hands-on, all-systems diagnostic as he has done so many times in his videos.)
Indications here are that your engine is just plain worn out, with significant carbon and moisture buildup internally. You could try the ATS Carbon Clean product that Scotty recommends for getting the carbon out and cleaning the fuel system to see if that helps. (Scotty has indicated it is a more effective product than the common off-the-shelf cleaners typically sold at parts stores.) However, part of driving old high-mileage beaters, something I've been doing for decades, is knowing when to let go.