general a/f ratio question

darkhorse · 12-28-2010, 11:58 AM

I have looked at many ford truck forums and none are up on eec stuff... I have a 94 bronco 5.8 seems to be speed density ...i am not shure (no maf) ....it runs way rich .... it has dual exhaust no cats which could contribute to this ... i timed it up to about 14 degrees opened up plug gap ...the regular efi small block ford junk and it runs much better....

changed all sensors (they were due anyway) it still smells like raw gas out the pipes, did ford set the ecm way rich from the factory ????? any ideas would be great....

EHardy1971 · 12-28-2010, 12:00 PM

Quote:

Originally Posted by darkhorse

I have looked at many ford truck forums and none are up on eec stuff... I have a 94 bronco 5.8 seems to be speed density ...i am not shure (no maf) ....it runs way rich .... it has dual exhaust no cats which could contribute to this ... i timed it up to about 14 degrees opened up plug gap ...the regular efi small block ford junk and it runs much better....

changed all sensors (they were due anyway) it still smells like raw gas out the pipes, did ford set the ecm way rich from the factory ????? any ideas would be great....

Yes, it's speed density if it has no MAF meter. What did the plugs look like when you pulled them out?

darkhorse · 12-28-2010, 12:03 PM

brown ,replaced with motorcraft standard copper plugs

86GTPONY · 12-28-2010, 12:22 PM

Speed density systems don't take too kindly to a bunch of big mods like heads & cam. Switching to a mass air set-up would be ideal, but you could probably get by with a a/f ratio gauge and an adjustable fpr to lean it out.

darkhorse · 12-28-2010, 12:34 PM

i dont know if they make a maf conversion for the truck w/ two blade throttle body .....will look into fuel press reg /a/f ratio thing

darkhorse · 12-28-2010, 01:10 PM

seems you have pointed me in the right direction .....after searching maf conversions....found speed density is "bank fired" , not true sefi which explains it all .... which will clear the way for heads cam ect.. all four injectors fire at same time instead of one at a time wow that sux might as well run a freakin carb....

THANKS.....

QWKSNKE · 12-28-2010, 01:19 PM

Quote:

Originally Posted by darkhorse

seems you have pointed me in the right direction .....after searching maf conversions....found speed density is "bank fired" , not true sefi which explains it all .... which will clear the way for heads cam ect.. all four injectors fire at same time instead of one at a time wow that sux might as well run a freakin carb....

THANKS.....

A large percentage of fuel injected vehicles are this way. Including MAF systems.

Also, just because you smell 'raw gas' at the tail pipes does not necessarily mean it is rich. It means that the combustion is not burning efficiently. Need to check all iginitions components.
Do like Eric said and pull the plugs, see which cylinders look 'off'

86GTPONY · 12-28-2010, 01:32 PM

Quote:

Originally Posted by QWKSNKE

A large percentage of fuel injected vehicles are this way. Including MAF systems.

Also, just because you smell 'raw gas' at the tail pipes does not necessarily mean it is rich. It means that the combustion is not burning efficiently. Need to check all iginitions components.
Do like Eric said and pull the plugs, see which cylinders look 'off'

Also, it shouldn't be too much a pita to convert to mass air. I used a $34 pigtail deal off ebay like this one: http://cgi.ebay.com/ebaymotors/Ford-...item4141fca8e7 and an a9l for my 86. I couldn't do a wire harness swap from an 89+ because it was totally different. Got it done in about 2 hours.

EHardy1971 · 12-28-2010, 02:48 PM

Somebody made a MAF conversion for these trucks (I have a '95 F-150 4x4 BTW), and may still make them. Summit used to carry them. Not ALL the F series/Broncos were bank fire. Being a '94 yours should be SEFI. The best way to check is by looking at the sticker on the computer where the bar code is. As was mentioned in another thread here recently, Ford changed a lot of stuff on the trucks from year to year, and sometimes at mid-year. But back on topic, like QWK posted, just because it smells like raw gas doesn't mean it's rich. If the plugs are brown, it sounds like the A/F is good to me.

darkhorse · 12-30-2010, 09:25 AM

does the sticker on ecm say "sefi" or do i need a decoder ring ? the more research i do the more i realize i will most likely have to live with the non sefi setup due to the fact that there is no ecm that will take care of 4x4/e4od/sefi/maf/ obd1 no vehicle existed with that setup from ford , the lightning is maf/e4od/sefi config,but the 4x4 wont go into low range according to most info avail...

a/f ratio is prob good in combustion chamber ..just seems like a waste of fuel ...

12-28-2010, 11:58 AM	#1
darkhorse Junior Member Join Date: Dec 2010 Posts: 20	general a/f ratio question I have looked at many ford truck forums and none are up on eec stuff... I have a 94 bronco 5.8 seems to be speed density ...i am not shure (no maf) ....it runs way rich .... it has dual exhaust no cats which could contribute to this ... i timed it up to about 14 degrees opened up plug gap ...the regular efi small block ford junk and it runs much better.... changed all sensors (they were due anyway) it still smells like raw gas out the pipes, did ford set the ecm way rich from the factory ????? any ideas would be great....

12-28-2010, 12:03 PM	#3
darkhorse Junior Member Join Date: Dec 2010 Posts: 20	brown ,replaced with motorcraft standard copper plugs __________________ '94 Bronco 5.8l eddie bauer (OJ edition)

12-28-2010, 12:22 PM	#4
86GTPONY Gone but not forgotten Join Date: May 2008 Location: 4/08/2013. Went to the man upstairs. RIP Posts: 955	Speed density systems don't take too kindly to a bunch of big mods like heads & cam. Switching to a mass air set-up would be ideal, but you could probably get by with a a/f ratio gauge and an adjustable fpr to lean it out. __________________ *-Don* 86GT (sleeping in the garage for now) 87 T-bird Turbo Coupe (daily driver) 87 Ranger ($100 work truck) Meat is murder!... Tasty, tasty murder.

12-28-2010, 12:34 PM	#5
darkhorse Junior Member Join Date: Dec 2010 Posts: 20	i dont know if they make a maf conversion for the truck w/ two blade throttle body .....will look into fuel press reg /a/f ratio thing __________________ '94 Bronco 5.8l eddie bauer (OJ edition)

12-28-2010, 01:10 PM	#6
darkhorse Junior Member Join Date: Dec 2010 Posts: 20	seems you have pointed me in the right direction .....after searching maf conversions....found speed density is "bank fired" , not true sefi which explains it all .... which will clear the way for heads cam ect.. all four injectors fire at same time instead of one at a time wow that sux might as well run a freakin carb.... THANKS..... __________________ '94 Bronco 5.8l eddie bauer (OJ edition)

12-28-2010, 02:48 PM	#9
EHardy1971 Trunk Monkey Join Date: Jun 2007 Location: Home Posts: 5,708	Somebody made a MAF conversion for these trucks (I have a '95 F-150 4x4 BTW), and may still make them. Summit used to carry them. Not ALL the F series/Broncos were bank fire. Being a '94 yours should be SEFI. The best way to check is by looking at the sticker on the computer where the bar code is. As was mentioned in another thread here recently, Ford changed a lot of stuff on the trucks from year to year, and sometimes at mid-year. But back on topic, like QWK posted, just because it smells like raw gas doesn't mean it's rich. If the plugs are brown, it sounds like the A/F is good to me. __________________ Eric 89 LX Coupe-Juiced 01 Lightning-Boost 06 TBSS

12-30-2010, 09:25 AM	#10
darkhorse Junior Member Join Date: Dec 2010 Posts: 20	does the sticker on ecm say "sefi" or do i need a decoder ring ? the more research i do the more i realize i will most likely have to live with the non sefi setup due to the fact that there is no ecm that will take care of 4x4/e4od/sefi/maf/ obd1 no vehicle existed with that setup from ford , the lightning is maf/e4od/sefi config,but the 4x4 wont go into low range according to most info avail... a/f ratio is prob good in combustion chamber ..just seems like a waste of fuel ... __________________ '94 Bronco 5.8l eddie bauer (OJ edition) Last edited by darkhorse; 12-30-2010 at 10:08 AM.