Final try before I bring it to a smog check

[sciphi]

Originally Posted By: mechtech2
Most returnless systems don't have the beloved shraeder valve anymore.


Both our returnless cars do.

And, this is most definitely a return-based fuel system.

 

[crazy8]

Panda, I recommend that you start with a pre test and see where you are at, then seek advice from there. I have helped many people through this process and it can be very hard and confusing with all of these opinions. I work in the industry and help many people on a daily basis. Goog luck.

 

[vssjim]

two bottles of Techron and premium gas would help with NOX emmisions 171 and 172 codes are lean and rich codes, I would worry about fuel pumps in these cars and MAF sensors./ Also on older fords those ground straps bolted on the radiator core support really matter and must be removed cleaned and tight period very important.

 

[Scott_Tucker]

Originally Posted By: PandaBear
Originally Posted By: irontom
What year is your car I had an older escort from 80's ignition module fried and the car ran as you say was easy to change had it happen twice.


93 1.9L


Ignition modules were a huge issue on these cars. It would not likely cause the symptoms you are describing, it usually causes a no-start or stalling.

You can still pull codes on these OBDI cars. As I remember you don't need a scanner so you might want to look that up.

 

[The_Jeff]

Originally Posted By: PandaBear


Originally Posted By: eljefino
Fresh oil will soak up HC. Water in the rad instead of antifreeze will help cool and cut NOx maybe.

The coolant temp, according to the gauge, goes into Normal but never above mid point of the "Normal" range. It is a separate temp sender unit that goes to the gauge than the temp sensor that goes into the ECU, so I would imagine the temperature is fine?


Yeah but water conducts heat slightly better and I was thinking of localized hot spots in the head and cylinder jackets not an overall temp. My old cutlass ciera ran maddeningly better on pure water than it did on EG coolant, less pinging. Give it a shot, it won't cost you much!

 

[PandaBear]

Originally Posted By: Scott_Tucker

Ignition modules were a huge issue on these cars. It would not likely cause the symptoms you are describing, it usually causes a no-start or stalling.

You can still pull codes on these OBDI cars. As I remember you don't need a scanner so you might want to look that up.


I pulled the code, it is 172 (lean O2 sensor not switching if I understand this correctly).

I also have recently fixed enough vacuum leak that I can now HEAR the exhaust notes (it used to be just a bunch of vacuum leaks and vibrations).

This morning, I notice that if I step on the gas more aggressively, I could hear a sudden exhaust note change that resemble a spray air can sound (although not very loud, you have to pay attention to hear it). If I do it enough times it would throw the CEL again. This happens in almost all rpm as long as the engine is under load and the gas pedal is pressed down a lot, it is too loud on highway to hear it but I think it is likely the same scenario when going on ramp.

I remember hearing a much louder version of this when I first got the car with crumbling plug wires and way worn out plugs. So am I reasonable to suspect the ignition (either coil or EDIS4 module)?

I'll rent a fuel pump diagnostic kit from Autozone and test out the fuel pressure one of these days to rule out the fuel pressure. I'm not sure if I have the ability to check the injector individually, but the old plugs were worn pretty evenly every other cylinder (due to waste spark).

 

[The_Jeff]

I think your catalytic convertor is plugged up.

The hiss is air escaping around the front of it.

The test is taking out your oxygen sensor (briefly) and seeing if it runs better.

 

[KB2008X]

Originally Posted By: eljefino
I think your catalytic convertor is plugged up.

The hiss is air escaping around the front of it.
The test is taking out your oxygen sensor (briefly) and seeing if it runs better.


That's a great idea. It's a quick and easy test. Just a little unburned fuel will foul a converter fairly soon and with the plugs and wires in such bad condition that is a likely scenario.

Keith

 

[ltslimjim]

Originally Posted By: eljefino
I think your catalytic convertor is plugged up.

The hiss is air escaping around the front of it.

The test is taking out your oxygen sensor (briefly) and seeing if it runs better.


Does one need to drive around with it unscrewed and unplugged, or just see if the idle improves, etc?

 

[The_Jeff]

Originally Posted By: ltslimjim
Originally Posted By: eljefino
I think your catalytic convertor is plugged up.

The hiss is air escaping around the front of it.

The test is taking out your oxygen sensor (briefly) and seeing if it runs better.


Does one need to drive around with it unscrewed and unplugged, or just see if the idle improves, etc?


I haven't done it so I don't know how much fire-hot exhaust is blasting other under hood stuff. But a strangled cat might let enough smoke by for a car to idle if it's determined. It throttles the whole system down while driving. Had THAT happen and knew instantly what was going on. Found a ping pong ball shaped "death star" looking thing in the inlet of my muffler of all places.

 

[Vikas]

A plugged up exhaust can be checked with a vacuum gauge. Trav posted a great link explaining how to use vacuum gauge effectively to find engine performance problem.

 

[PandaBear]

So I tested the fuel pressure (correctly or incorrectly) to be 2PSI, as stated in this separate thread.

https://bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=2730731#Post2730731

If I take out the O2 wouldn't it be running super rich?

 

[PandaBear]

smog passed:


15mph: (max, ave, meas)
HC 64, 26, 64
CO 0.38, 0.14, 0.26
NO 501, 163, 254

25mph: (max, ave, meas)
HC 40, 16, 16
CO 0.38, 0.13, 0.14
NO 535, 165, 194


Seems like other than 15mph HC the engine is running ok. So the high throttle high load / rpm lean CEL is not affecting my 15/25mph smog result.

Since this is going to be a car at work for lunch / doctor office only. I don't think I'll spend the effort to pin point the CEL unless it is easy and obvious. Does this conclude that there's no vacuum leak? or is the fuel pump / pressure good? or the CAT is not plugged? or all the sensor working fine?

Could this point to something less obvious like EGR condition? or coil not holding up at high voltage (high throttle, high load, etc)?

 

[PandaBear]

Turns out the MAF was so gummed up that just spraying will not clean it. I bought a security hex key (T20) to open it up and have to gently scrub the 2 wires with Q tip and non chlorinated brake fluid to remove the deposit. Just spraying it directly did nothing. Now the CEL is gone for good.

Thanks for all the helps.