Nick7 Posted March 14, 2008 Report Share Posted March 14, 2008 today I decided that I was going to try to figure out y I have been getting spark knock with 93 and not 110 octane. So I installed my new fuel gauge and the fuel pressure was normal around 34-36psi. But when I rev the engine at idle when the car was warm, the fuel pressure dropped dang near 25psi? So I install my new AFPR and it did the same thing, so I increased the fuel pressure to 45psi and it still dropped, but not as much around 38-40 psi. I was wondering what can cause this? I have a new 255 walbro inline pump. I havent changed the the fuel filter in 5k miles. I was wondering do I need to install a new stock filter or go with a performance fuel filter? Also I have a fuel cell with a filter in between the cell and the pump, but it is autozone brand too. I need help fast please.. thanks. Link to comment Share on other sites More sharing options...
Chad Posted March 15, 2008 Report Share Posted March 15, 2008 Are you MPI or still using the stock TBI setup? What vacuum source is the FPR hooked up to (stock or some other port)? Link to comment Share on other sites More sharing options...
Nick7 Posted March 15, 2008 Author Report Share Posted March 15, 2008 Are you MPI or still using the stock TBI setup? What vacuum source is the FPR hooked up to (stock or some other port)? I still got TBI. I bought a AFPR from mookeek, so it hooks up like the stock one.. Link to comment Share on other sites More sharing options...
Edde Posted March 15, 2008 Report Share Posted March 15, 2008 Sure points to restricted flow if you ask me. That or lack of boost signal on the FPR. Link to comment Share on other sites More sharing options...
JustPaus_88TSi Posted March 15, 2008 Report Share Posted March 15, 2008 Umm.. What does the fuel pressure do when you're under load and not just revving up in neutral? Link to comment Share on other sites More sharing options...
Edde Posted March 15, 2008 Report Share Posted March 15, 2008 Umm.. What does the fuel pressure do when you're under load and not just revving up in neutral? Yikes. Good call. I totally missed that :character0285: Link to comment Share on other sites More sharing options...
Nick7 Posted March 15, 2008 Author Report Share Posted March 15, 2008 Yikes. Good call. I totally missed that :character0285: Dont know yet i havent put on digital gauge in. I am think it could be in the filters, because shes acting like shes sluggish alittle. Link to comment Share on other sites More sharing options...
Nick7 Posted March 15, 2008 Author Report Share Posted March 15, 2008 Dont know yet i havent put on digital gauge in. I am think it could be in the filters, because shes acting like shes sluggish alittle. I figured it out. first my spark plug gap was at .040, so I changed it to .020 with new stock plugs instead of colder NGK plug and lowered the fuel psi from 45 psi to 39psi and it pulls even harder than it did when it was 25 degrees colder outsde.. How ever the fuel pressure still drops at idle, but i need to see what its doing at wot under boost.. I got to install my digital gauge inside the car first though. Link to comment Share on other sites More sharing options...
Chad Posted March 16, 2008 Report Share Posted March 16, 2008 Move your gap back up to .036" +/- . .020 is only for those runnign megga boost, and they dont last that long any way. You will foul them quickly at that gap. Link to comment Share on other sites More sharing options...
Caliber308 Posted March 16, 2008 Report Share Posted March 16, 2008 Move your gap back up to .036" +/- . .020 is only for those runnign megga boost, and they dont last that long any way. You will foul them quickly at that gap. If you dont know exactly what NGK plug hes running or boost psi you cant recommend gap!!!!! NGK BPR7ES-11: .035 TO .039 NGK BPR6ES-11: .039 TO .043 Decrease gap even more when running higher than factory boost(10 psi) Which you told me in a earlier post you are. CALIBER 308 Link to comment Share on other sites More sharing options...
JustPaus_88TSi Posted March 16, 2008 Report Share Posted March 16, 2008 If you dont know exactly what NGK plug hes running you cant recommend gap!!!!! CALIBER 308 Umm... He stated which plugs. I figured it out. first my spark plug gap was at .040, so I changed it to .020 with new stock plugs instead of colder NGK plug and lowered the fuel psi from 45 psi to 39psi and it pulls even harder than it did when it was 25 degrees colder outsde.. How ever the fuel pressure still drops at idle, but i need to see what its doing at wot under boost.. I got to install my digital gauge inside the car first though. There isn't a plug made for the g54b that says to run a .020 gap.. It's more likely that your ignition system isn't as healthy as it should be, as opposed to blowing out the spark from a BPR6, 7, or 8 that gapped in the mid-high 30's.. Even 21psi from the 12a and 18-19psi from the s16g didn't blow out my spark with BPR7ES plugs at 0.038 Link to comment Share on other sites More sharing options...
Caliber308 Posted March 16, 2008 Report Share Posted March 16, 2008 Umm... He stated which plugs. Im running 8s at .032 and 15psi boost so I guess im wrong in not gapping them in the mid to upper .030s.lol. And the question was never asked as to how much boost hes running to determine gap. I know!! p.s. John, are you a member of the "Lets follow Cals posts around" club. If so, Do you guys all talk at the same time about which of my posts get attacked next????? CALIBER 308 Link to comment Share on other sites More sharing options...
emagdnim Posted March 16, 2008 Report Share Posted March 16, 2008 First off, the guage itself may be in question, but you stated your going to install another... so thats a good start. I'd recommend putting the stock AFPR back on and see if it differs from the mookie unit. If the stock one is bad, buy a real AFPR. (Aeromotive) If that doesn't work, the filters you installed don't flow enough for the 255. if the filters don't fix the problem you have a faulty 255. The 255 will overrun that wimpy mookie FPR... so replace the FPR with a aeromotive anyway. I believe Indiana's website has the walk-threw for the install. While at idle, the FPR should rise when you give it gas, DO NOT drive the car until you see that happen. You stated you have a fuel cell, is the car still on the stock fuel lines as well? if not did you flush the stockers? Link to comment Share on other sites More sharing options...
Caliber308 Posted March 16, 2008 Report Share Posted March 16, 2008 While at idle, the FPR should rise when you give it gas, DO NOT drive the car until you see that happen. ????????????????? CALIBER 308 Link to comment Share on other sites More sharing options...
Chad Posted March 16, 2008 Report Share Posted March 16, 2008 If you dont know exactly what NGK plug hes running or boost psi you cant recommend gap!!!!! NGK BPR7ES-11: .035 TO .039 NGK BPR6ES-11: .039 TO .043 Decrease gap even more when running higher than factory boost(10 psi) Which you told me in a earlier post you are. CALIBER 308 Gap needs differ depending on intended use. Those NGK recomended ranges are for bone-stock setups. Notice those are also ranges, and then notice I put " +/- " after my values. Now notice even you don't follow those ranges since you are at .032 yourself. I can quote a range just like the manufacturer does. If I'm wrong, wouldn't NGK be wrong too? Do you think NGK owes him a phone call askign him what mods he has before they can reccoment a gap? No, it's just a "start here and make adjustments as needed". Given your 35 years of automotive experiance, I'm sure you can agree that a spec'd gap is a suggestion, not a hard set rule - do this or else - type thing. It is the accepted norm (yes, I know you won't accept this statement) that .036 +/- is the best place to start with an NGK, wether it be the 6, 7 or 8. If you coudl search the origional site, this was common knowledge even before I came here 10 years ago, so it's not somethign that I made up "because I know it all". I've taken that advice and hag excelent results from it, as have many. Runnign a 6ES at .036 +/- is not going to "not work" just because the recomended gap is .041 +/-. It will however not work right if you gapped it to .020 as he did. I didn't tell him "go get the FSM and see what it says" I told him to increase gap from .020 and gave a range to shoot for. So who is following whom now anyway :gun: Link to comment Share on other sites More sharing options...
Nick7 Posted March 16, 2008 Author Report Share Posted March 16, 2008 Gap needs differ depending on intended use. Those NGK recomended ranges are for bone-stock setups. Notice those are also ranges, and then notice I put " +/- " after my values. Now notice even you don't follow those ranges since you are at .032 yourself. I can quote a range just like the manufacturer does. If I'm wrong, wouldn't NGK be wrong too? Do you think NGK owes him a phone call askign him what mods he has before they can reccoment a gap? No, it's just a "start here and make adjustments as needed". Given your 35 years of automotive experiance, I'm sure you can agree that a spec'd gap is a suggestion, not a hard set rule - do this or else - type thing. It is the accepted norm (yes, I know you won't accept this statement) that .036 +/- is the best place to start with an NGK, wether it be the 6, 7 or 8. If you coudl search the origional site, this was common knowledge even before I came here 10 years ago, so it's not somethign that I made up "because I know it all". I've taken that advice and hag excelent results from it, as have many. Runnign a 6ES at .036 +/- is not going to "not work" just because the recomended gap is .041 +/-. It will however not work right if you gapped it to .020 as he did. I didn't tell him "go get the FSM and see what it says" I told him to increase gap from .020 and gave a range to shoot for. So who is following whom now anyway :gun: well. I got a 19C turbo running 14lbs. of boost. However my timing is perfect. It hits 10btdc and advances no more then 30 degrees. However i am running 110octane too.?? And I did some reading on the fuel pressure. Its not suppose to increase fp until it sees vaccum. Link to comment Share on other sites More sharing options...
JustPaus_88TSi Posted March 16, 2008 Report Share Posted March 16, 2008 Im running 8s at .032 and 15psi boost so I guess im wrong in not gapping them in the mid to upper .030s.lol. And the question was never asked as to how much boost hes running to determine gap. I know!! 0.032 is a far cry from 0.020.. And yes, you could open the gap up to 0.035-0.036 or so and have a more complete burn. 15psi from a 550cfm turbo won't even blow out a 0.040. p.s. John, are you a member of the "Lets follow Cals posts around" club. If so, Do you guys all talk at the same time about which of my posts get attacked next????? CALIBER 308 Yeah, that's exactly what I need to waste my time on. Me attacking you would look much much different, as there'd be no mistake about it. I'm sticking to the facts. All I did was post info that you obviously missed, and added my experiences into the mix. If you post something that's questionable, you're going to get called on it.. Period. There's no playing favorites, just correct info so the original poster can get his issues squared away without just throwing money at it and hoping for the best. Take off the tin foil hat, there's no conspiracy. Link to comment Share on other sites More sharing options...
Chad Posted March 16, 2008 Report Share Posted March 16, 2008 It's supposed to increase the fuel pressure 1 PSI for every PSI of manifold pressure. Baseline is 36 ish. If you are at 14 PSI, you should see 36+14= 50 PSI, and not a single bit less. This beign said, you should also see it drop with high vac like decelerating or idling. At idle you are at about -5 PSI, 36-5=31 PSI. at full decel you are at about -12 PSI, 36-12=24 PSI. If you are not seeing these values, you need to address the supply (pump/filters) or the regulator before you do any more boosting. And for a 19C, I'd start my gap at .036 and work from there. If you are gettign spark knock at .036, you may be too lean and it may not be spark knock at all. Retard your timing temporarily to about 6* at idle and see if the problem gets better or stays the same. If it gets better, you may be too lean, less timign reduces knock. If it stays the same, you may have weak spark. One friends car had issues with weak spark, turned out to be a bad plug wire. We found it wtih an Ohm meter, one read way high compared to the others Link to comment Share on other sites More sharing options...
emagdnim Posted March 16, 2008 Report Share Posted March 16, 2008 Also, when the car is idling and you pull the vac hose off, if it don't drop that fast or very much it's a direct result in the pump overrunning the FPR. Link to comment Share on other sites More sharing options...
Caliber308 Posted March 16, 2008 Report Share Posted March 16, 2008 Gap needs differ depending on intended use. Those NGK recomended ranges are for bone-stock setups. Notice those are also ranges, and then notice I put " +/- " after my values. Now notice even you don't follow those ranges since you are at .032 yourself. I can quote a range just like the manufacturer does. If I'm wrong, wouldn't NGK be wrong too? Do you think NGK owes him a phone call askign him what mods he has before they can reccoment a gap? No, it's just a "start here and make adjustments as needed". Given your 35 years of automotive experiance, I'm sure you can agree that a spec'd gap is a suggestion, not a hard set rule - do this or else - type thing. It is the accepted norm (yes, I know you won't accept this statement) that .036 +/- is the best place to start with an NGK, wether it be the 6, 7 or 8. If you coudl search the origional site, this was common knowledge even before I came here 10 years ago, so it's not somethign that I made up "because I know it all". I've taken that advice and hag excelent results from it, as have many. Runnign a 6ES at .036 +/- is not going to "not work" just because the recomended gap is .041 +/-. It will however not work right if you gapped it to .020 as he did. I didn't tell him "go get the FSM and see what it says" I told him to increase gap from .020 and gave a range to shoot for. So who is following whom now anyway :gun: Hows it feel when your on the receiving end!!!!!! CALIBER 308 Link to comment Share on other sites More sharing options...
emagdnim Posted March 16, 2008 Report Share Posted March 16, 2008 Can you please stop with the BS? How is your post helping this guy? Link to comment Share on other sites More sharing options...
Chad Posted March 16, 2008 Report Share Posted March 16, 2008 And yes, you could open the gap up to 0.035-0.036 or so and have a more complete burn. 15psi from a 550cfm turbo won't even blow out a 0.040. I've run a T-4 60-1 at 23 PSI (~950 CFM) running gap at .042 just to see, I didnt' notice any ignition problems (blosn out spark). I do however chose to run .032-.034 to reduce the chances of blow out. I also seem to fowel them less often from running lots of fuel though the motor (I rum the motor very hard, and sometimes too rich). Shorter gaps = more intense spark, which can help keep the gap clean. If your ignitions system and mixture is right and you aren't runnign crazy boost (above 20), there will be little gain from shortenign the gap a whole lot. If you shorten your gap from .040 to .020 and see signifigaint gains, you have other issues. Link to comment Share on other sites More sharing options...
Nick7 Posted March 16, 2008 Author Report Share Posted March 16, 2008 I've run a T-4 60-1 at 23 PSI (~950 CFM) running gap at .042 just to see, I didnt' notice any ignition problems (blosn out spark). I do however chose to run .032-.034 to reduce the chances of blow out. I also seem to fowel them less often from running lots of fuel though the motor (I rum the motor very hard, and sometimes too rich). Shorter gaps = more intense spark, which can help keep the gap clean. If your ignitions system and mixture is right and you aren't runnign crazy boost (above 20), there will be little gain from shortenign the gap a whole lot. If you shorten your gap from .040 to .020 and see signifigaint gains, you have other issues. Well I think that it could have been I had the fuel pressure to high. I had it at 45psi and lowered it back down to 39. There isnt fuel cutting or spark knocking anymore. It pulls to 5800rpms with nothing like not enough fuel from stopping it. It doesnt fall on its face what so ever. However I will be getting my wideband wednesday this week coming. I am going to install my FP gauge into my car today and wideband this week. I know even though it feels fine, there could be sometime always wrong without seeing whats it really doning.. I got to install the rest of my stuff before i actually know what it is doing. thanks Link to comment Share on other sites More sharing options...
Nick7 Posted March 16, 2008 Author Report Share Posted March 16, 2008 Well I think that it could have been I had the fuel pressure to high. I had it at 45psi and lowered it back down to 39. There isnt fuel cutting or spark knocking anymore. It pulls to 5800rpms with nothing like not enough fuel from stopping it. It doesnt fall on its face what so ever. However I will be getting my wideband wednesday this week coming. I am going to install my FP gauge into my car today and wideband this week. I know even though it feels fine, there could be sometime always wrong without seeing whats it really doning.. I got to install the rest of my stuff before i actually know what it is doing. thanks oh, I also I did notice alittle diference in power when i did what i did. By changing the plug gap, changing FP. and the timing is hitting perfect. Couldnt ask for better. Link to comment Share on other sites More sharing options...
Chad Posted March 16, 2008 Report Share Posted March 16, 2008 Sounds like you are on the right track, monitoring FP and A/F will mke for a much better diagnosis. I wouldn't mess with it much untill you can get those gages in. A 19C can do a lot of damage quick if your mixtue is off. Link to comment Share on other sites More sharing options...
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