need smog advice- car needs to get referee'd

[BLITZ]

i have a 93 cobra engine that wont pass smog. im having problems specifically with the EGR valve. im new to mustangs so im just trying to get some advice here. i was told by my last mechanic that i would need to change the computer as well?

does anyone have experience with smog/EGR? Any help would greatly be appreciated. Thanks in advance.

p.s. if ppl who happen to read this are from so cal, do you guys know of any smog shops/mechanics that would be good at handling this?

 

[jrichker]

Step 1.) Dump the codes and see what the computer says is wrong…

Here's the link to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great.

See http://www.troublecodes.net/Ford/
OR
See http://www.dalidesign.com/hbook/eectest.html for more descriptive help
OR
See http://www.mustangworks.com/articles/electronics/eec-iv_codes.html

IF your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.

Codes have different answers if the engine is running from the answers that it has when the engine isn't running. It helps a lot to know if you had the engine running when you ran the test.

Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes.

For those who are intimidated by all the wires & connections, see http://www.actron.com/product_detail.php?pid=16153 for what a typical hand scanner looks like. Normal retail price is about $30 or so at AutoZone or Walmart.

Or for a nicer scanner see http://www.midwayautosupply.com/detailedproductdescription.asp?3829 – It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $33.

Computers rarely fail, usually it is a sensor or adjustment that needs attention. That's why it is important to dump the codes.

Step 2.) Post the results & we will try to help. There are 5 different codes associated with the EGR system & they all have different causes & cures.

EGR system theory...
The EGR system has a vacuum source (line from the intake manifold), a computer operated electrical vacuum regulator (EVR), the EGR valve and the passages in the heads and intake manifold that route exhaust gas to the EGR valve. The computer uses RPM, Load, and some other factors to tell the vacuum regulator to pass vacuum to open the EGR valve. The EGR sensor tells the computer how far the EGR valve is open. Then computer adjusts the signal sent to the EGR vacuum regulator to hold, increase or decrease the vacuum.

The EGR shuts off at Wide Open Throttle (WOT), so it has minimal effect on performance. The addition of exhaust gas drops combustion temperature, increases gas mileage and reduces the tendency of the engine to ping.

 

[BLITZ]

from what i understand, the engine was running. but the thing is, its a 1993 5.0 engine in a miata. i was told that replacing all the egr hoses and replacing the computer should do the job.

its already really close to being smog legal- it has 2 cats that another referee said was required (but didnt do the job).

ill look at those sites and try posting up some codes. thanks for the response.

 

[cjones]

what are your emission readings?? and maximums?? did you GP??

O2
NOx
CO
CO2
HC


Do you have a BAR label or are you trying to get one??

 

[SamSnyder]

If you have 4 cats, I assume it is a stock h-pipe? If so, I would suspect old age, since fresh cats (which only come in 2's on BBK/MAC/Steeda, etc. replacement h-pipes) make a HUGE improvement in out-the-pipe emissions, even if "stock" consists of 4 cats. (I know, since my Steeda and BBK 2-cat h-pipes both did better than the old 4-cat stocker when the numbers were revealed). You may be entitled to use a 2-cat "replacement" h-pipe if your stocker has enough miles on it (I think the rules call for a certain number of miles PLUS someone has to declare your stocker operationally dead, and you can replace the cats with any suitable "replacement" cats, i.e., a BBK h-pipe. If your numbers flunk, I think that ought to qualify as operationally dead). They're also right that the EGR valve can affect things. Just removing mine and hosing it old long and hard with Gummout noticeably improved the idle characteristics, which probably translates into smog number improvements (don't forget to buy a new gasket, since you will surely break the old one). Those 2 things, plus making sure the cats are good and hot when they run the test are about the biggest things I've encountered. Fixing any bad vacuum hose hookups can't hurt either. As to the computer, the '93 Cobra was a different part number to account for for the bigger mass air meter and 24 lb. injectors, although the word is it's actually an inferior computer that suffers from off-idle hestitation. Most people just get mass air meters tuned to compensate for bigger meters, throttle bodies and injectors running on the stock 19 lb. computer. But if the referees are demanding that you get an actual '93 Cobra computer to go with a '93 Cobra engine, they may force you to do it just because the part numbers tell them to. If so, be prepared to grab your ankles, since the '93 Cobra computers are somewhat scarce. Just FYI, my GT40 iron head/E303 cam/Mac shorties/MSD6a/BBK 2.5" cat h-pipe, '90 LX hatch (which is absolutely Cal. smog legal, including all Executive Order numbers), blows cleaner numbers out the pipes than my totally stock '90 LX convertible.

 

[BLITZ]

thanks for the point in the right direction guys. im trying to get a bar label.

i checked and it has bbk cats. car passed at a smog station, but failed with the referee (visual passed) during the higher rpm dyno test. it failed on

referee
NO (PPM)
15 mph (1546 rpm) 2509 max 757
25 mph (2472 rpm) 1634 max 696

smog station (1 mo. prior)
NO (PPM)
15 mph (1469 rpm) 0463
25 mph (2393 rpm) 0685


all the other readings passed, but i can post it if it helps.

sam, how can i differentiate if my ecm is for a cobra? i looked at it and couldnt tell. thanks again guys. i hope to solve all of this so i get to actually drive the car on the streets...

 

[SamSnyder]

Regular 5.0 computer is known as the A9L (along with A9M and A9P, which have to do with the specific year and transmission). The Cobra computer is a X3Z. Here is a post on another web site talking about it. You could probably find an X3Z on ebay. http://www.fordmuscle.com/phpBB/viewtopic.php?word=A9L&topic=11503&forum=17

 

[cjones]

please post the other levels as well.

NO only occurs when cyl temp is above 2500*F. (EGR system, cooling system, lean A/F mix, anthing else that causes the engine to run hot) can cause it.

 

[BLITZ]

Sam,

the ecm's code is "X0X" ? i would xoxox to have all this figured out i guess i could call a ford dealership to try to track down what model the ecm was for. i was reading that post you linked- cobra owners try to tune the X3Z to A9L specs? which would you recommend?

Cjones,

15mph (1546 rpm) / 25 mph (2472 rpm)
%C02: 13.1 / 13.4
%02: 2.6 / 2.0

passed
HC (PPM): 86 / 24
max 105 / 80
GP 280 / 230

passed
CO(%): 0.02 / 0.00
max 0.69 / 0.56
GP 2.19 / 2.06

failed
NO (PPM): 2509 / 1634
max 757 / 696
GP 1943 / 1743


this is all new to me, so im picking this up as i go. see any red flags?

 

[cjones]

looks like you may be a bit lean.

since you don't have AIR, the O2 is elevated for the CO you have.

but check the EGR system first:

to check the EGR valve:
bring the engine to normal temp.
connect a vacuum pump to the EGR Valve
apply 5in vacuum to the valve.
if engine stumbled or died then EGR Valve and passage(there is a passageway through the heads and intake) are good.
if engine did NOT stumble or die then either the EGR Valve is bad and/or the passage is blocked.
if engine stumbled, connect vacuum gauge to the hose coming off of the EGR Valve
snap throttle to 2500 rpms (remember snap the throttle don't hold it there).
did the vacuum gauge show about 5in vacuum?

if not, check for manifold vacuum at the EGR vacuum valve.
if you have manifold vacuum then connect vacuum gauge to the EGR valve side of the vacuum valve and snap throttle to 2500rpms.
should read about 5in vacuum


let me know the results of the test and we'll go from there.

PS i go into the hospital for almost a week on Tuesday morning (knee replacement).

i'm not sure of the comp code

 

[BLITZ]

thanks again, cjones.

if i dont post up by then, best of luck on the knee replacement.

 

[cjones]

thanks again, cjones.

if i dont post up by then, best of luck on the knee replacement.

Thank You.

take care,

CJ