Reducing fuel smell in tune
Reducing fuel smell in tune My 6.0/turbo '84 Jaguar has been great to cruise around in as a summer ride, but the one thing I'd like to improve is the exhaust smell. The thing stinks like fuel all the time and will water your eyes unless you're doing at least 30.
I have read that EOIT (end of injection timing) can be played with to prevent raw fuel going out the tailpipe. Any other tips on tune tweaks to make it more enjoyable? Unfortunately the car is stored for the winter so I don't have access to be able to post the tune.
Setup:
Gen 3 6.0, bone stock other than Sloppy Stage 2 cam, Specs: 228/230 .585"/.585" 112 LSA
Fuel: 93 and pump ethanol (E30 up to E70) depending on availability
Injectors: Siemens Deka 80s
Exhaust: 3" downpipe, Flowmaster 3" 3-way catalytic converter (FLO-2000130)
ECU: Terminator X, self tuned on the street
I welded in the cat hoping it would knock down the smell but unfortunately it seems to have made no difference.
PFA
I have read that EOIT (end of injection timing) can be played with to prevent raw fuel going out the tailpipe. Any other tips on tune tweaks to make it more enjoyable? Unfortunately the car is stored for the winter so I don't have access to be able to post the tune.
Setup:
Gen 3 6.0, bone stock other than Sloppy Stage 2 cam, Specs: 228/230 .585"/.585" 112 LSA
Fuel: 93 and pump ethanol (E30 up to E70) depending on availability
Injectors: Siemens Deka 80s
Exhaust: 3" downpipe, Flowmaster 3" 3-way catalytic converter (FLO-2000130)
ECU: Terminator X, self tuned on the street
I welded in the cat hoping it would knock down the smell but unfortunately it seems to have made no difference.
PFA
Teching In
Joined: Jul 2024
Posts: 13
Likes: 6
I understand your feelings on this, I once had a 3v mustang without cats and it eventually made the car unenjoyable to daily drive.
I bet the catalytic converter is not "lighting off" since it's understandably a good ways behind a turbo. How far downstream is it? Is the plumbing of the wastegate back into the down pipe or open?
Very cool ride btw!
I bet the catalytic converter is not "lighting off" since it's understandably a good ways behind a turbo. How far downstream is it? Is the plumbing of the wastegate back into the down pipe or open?
Very cool ride btw!
TECH Fanatic
Joined: Jul 2022
Posts: 1,032
Likes: 389
From: Alaska
In for answers.
Similar problem with "STINKY EXHAUST" on daily driver Suburban, even went as far as weld in High Flow CAT just after Down-pipe.
I have been told that RETARDING the spark at idle, and cruise can HEAT th cat and make it more efficient, but I like the throttle response I get from spark ADVANCE.
Let me know, keep us posted on the exact changes you attempt with EOIT.
My reading on the subject just confuses me more. the actual settings seem counter intuitive- HPTuners rendition of GM's oem line codes are less than transparent.
Similar problem with "STINKY EXHAUST" on daily driver Suburban, even went as far as weld in High Flow CAT just after Down-pipe.
I have been told that RETARDING the spark at idle, and cruise can HEAT th cat and make it more efficient, but I like the throttle response I get from spark ADVANCE.
Let me know, keep us posted on the exact changes you attempt with EOIT.
My reading on the subject just confuses me more. the actual settings seem counter intuitive- HPTuners rendition of GM's oem line codes are less than transparent.
I understand your feelings on this, I once had a 3v mustang without cats and it eventually made the car unenjoyable to daily drive.
I bet the catalytic converter is not "lighting off" since it's understandably a good ways behind a turbo. How far downstream is it? Is the plumbing of the wastegate back into the down pipe or open?
Very cool ride btw!
I bet the catalytic converter is not "lighting off" since it's understandably a good ways behind a turbo. How far downstream is it? Is the plumbing of the wastegate back into the down pipe or open?
Very cool ride btw!
In for answers.
Similar problem with "STINKY EXHAUST" on daily driver Suburban, even went as far as weld in High Flow CAT just after Down-pipe.
I have been told that RETARDING the spark at idle, and cruise can HEAT th cat and make it more efficient, but I like the throttle response I get from spark ADVANCE.
Let me know, keep us posted on the exact changes you attempt with EOIT.
My reading on the subject just confuses me more. the actual settings seem counter intuitive- HPTuners rendition of GM's oem line codes are less than transparent.
Similar problem with "STINKY EXHAUST" on daily driver Suburban, even went as far as weld in High Flow CAT just after Down-pipe.
I have been told that RETARDING the spark at idle, and cruise can HEAT th cat and make it more efficient, but I like the throttle response I get from spark ADVANCE.
Let me know, keep us posted on the exact changes you attempt with EOIT.
My reading on the subject just confuses me more. the actual settings seem counter intuitive- HPTuners rendition of GM's oem line codes are less than transparent.
My 6.0/turbo '84 Jaguar has been great to cruise around in as a summer ride, but the one thing I'd like to improve is the exhaust smell. The thing stinks like fuel all the time and will water your eyes unless you're doing at least 30.
I have read that EOIT (end of injection timing) can be played with to prevent raw fuel going out the tailpipe. Any other tips on tune tweaks to make it more enjoyable? Unfortunately the car is stored for the winter so I don't have access to be able to post the tune.
Setup:
Gen 3 6.0, bone stock other than Sloppy Stage 2 cam, Specs: 228/230 .585"/.585" 112 LSA
Fuel: 93 and pump ethanol (E30 up to E70) depending on availability
Injectors: Siemens Deka 80s
Exhaust: 3" downpipe, Flowmaster 3" 3-way catalytic converter (FLO-2000130)
ECU: Terminator X, self tuned on the street
I welded in the cat hoping it would knock down the smell but unfortunately it seems to have made no difference.
PFA
I have read that EOIT (end of injection timing) can be played with to prevent raw fuel going out the tailpipe. Any other tips on tune tweaks to make it more enjoyable? Unfortunately the car is stored for the winter so I don't have access to be able to post the tune.
Setup:
Gen 3 6.0, bone stock other than Sloppy Stage 2 cam, Specs: 228/230 .585"/.585" 112 LSA
Fuel: 93 and pump ethanol (E30 up to E70) depending on availability
Injectors: Siemens Deka 80s
Exhaust: 3" downpipe, Flowmaster 3" 3-way catalytic converter (FLO-2000130)
ECU: Terminator X, self tuned on the street
I welded in the cat hoping it would knock down the smell but unfortunately it seems to have made no difference.
PFA
https://forums.holley.com/forum/holl...e-tuning/page7
Use this spreadsheet for injector end angle table post #96. All instructions are included. Just add an advanced 2D table
https://forums.holley.com/forum/holl...e-tuning/page7
https://forums.holley.com/forum/holl...e-tuning/page7
Last edited by NicD; Dec 19, 2025 at 11:12 AM.
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That is a good spreadsheet to put you in the ballpark and it's easy enough to make adjustments in the idle specific areas if necessary. The method he uses targets the beginning of injection right after the exhaust valve closes to avoid the overlap area (when the intake and exhaust valve are both open). It has lots of assumptions built in like port velocity, etc and while you can make adjustments to it you are just guessing unless you are using some sort of engine analyzer program. Either way, much better than the built in Holley calculator that tries to center the injection pulse on the ICL which I really don't like. The larger the injectors the more of a difference this will all make at lower pulse widths. Just keep in mind that it may also be beneficial to inject earlier on top of the intake valve when the engine is cold to help the fuel vaporize on the back of the hot valve and then roll it back at operating temperature, just like the OEMs do it (with no overlap of course). Just as a test you could set it static at -90 which is 450 deg EOI and see if that helps, pretty much guarantee no overlap there ever.
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