Talyn
NAXJA Forum User
- Location
- Radford, Communistwealth of Virginia
I still think 30s are too large and you can't actually tell your AFR with out a wide band.
help! stroker running rough
- Thread starter GoliathJeeper
- Start date
Talyn
NAXJA Forum User
- Location
- Radford, Communistwealth of Virginia
You are telling him to do something that you have no proof if it works or not. You don't know your true AFR and you don't know what the short term and long term fuel trims are. I had a 68-231-4 cam in my 4.6L stroker with Mustang cobra injectors (~27lb) and I have a wideband. With out MAP modifications they ran too rich in WOT. This was proven on both a long rod stroker with good quench and a short rod with sloppy quench.
At a hot idle the PCM is reading off the O2 sensors to maintain a 14.7:1 fuel ratio. Even a stock injector can accomplish that. So you saying that the 30lb injectors did something at idle indicates that they may even be too large, or the stock injectors were just plugged up. Most of the time unless you are past about 75% throttle or so the PCM will be shooting for 14.7:1.
Plugs should not be tan in the short term you have run them. Also, looking at the porcelain tip is not where you determine AFR, that would be at the very base of the porcelain where it meets the plug body.
His problems are not related to injector sizing. Possibly they could be clogged though.
Plugs are also a pretty bad indicator of AFR in a computer controlled fuel injection system using unleaded gas. And you won't get a good reading anyhow unless you do a WOT run on a hot engine and shut it down at the very end to read the plugs.
At a hot idle the PCM is reading off the O2 sensors to maintain a 14.7:1 fuel ratio. Even a stock injector can accomplish that. So you saying that the 30lb injectors did something at idle indicates that they may even be too large, or the stock injectors were just plugged up. Most of the time unless you are past about 75% throttle or so the PCM will be shooting for 14.7:1.
Plugs should not be tan in the short term you have run them. Also, looking at the porcelain tip is not where you determine AFR, that would be at the very base of the porcelain where it meets the plug body.
His problems are not related to injector sizing. Possibly they could be clogged though.
Plugs are also a pretty bad indicator of AFR in a computer controlled fuel injection system using unleaded gas. And you won't get a good reading anyhow unless you do a WOT run on a hot engine and shut it down at the very end to read the plugs.
GoliathJeeper
NAXJA Forum User
- Location
- Winnfield, Louisiana
new lifters, cam, pushrods, rockers, and valves were used due to the parts being worn out of spec. the probelm occurs right off idle as soon as the rpm's are increased. no matter if it's a cold start or if the engine has been running for 10 minutes (that's about the longest I've allowed it to run) I noticed the temp rises very quickly which I figured was another indication of a lean mixture. I really don't care for the splice in O2 sensors myself bu there was not a downstream O2 sensor installed and no one in town had a factory style unit so just for the sake of getting it together and running I used it. which I feel very confident it was installed correctly because I used a voltmeter to double check myself on the wiring. also the fact that the ds o2 sensor doesn't even start reading until a few mins after warmup rules out the fact it could be faulty or miswired. since the problem occurs imediatly upon a cold start up.
oh and as far as the timing set. new gears and chain was installed. straight from a dealer. so I know they're quality. and OE.
oh and as far as the timing set. new gears and chain was installed. straight from a dealer. so I know they're quality. and OE.
Last edited:
Talyn
NAXJA Forum User
- Location
- Radford, Communistwealth of Virginia
Did you break in the cam correctly? A down stream (after cat) O2 sensor has no bearing on the AFR.
GoliathJeeper
NAXJA Forum User
- Location
- Winnfield, Louisiana
broke in the cam using non-syn oil. primed the oil system used ether to ensure a fast start. brought it up to 1500 (that was really as high as the motor could stand without backfiring too badly. and fluctuated the rpm's to break in the cam. changed oil and filter and proceeded to work on the lean mixture issue.
GoliathJeeper
NAXJA Forum User
- Location
- Winnfield, Louisiana
broke in the cam using non-syn oil. primed the oil system used ether to ensure a fast start. brought it up to 1500 (that was really as high as the motor could stand without backfiring too badly. and fluctuated the rpm's to break in the cam. changed oil and filter and proceeded to work on the lean mixture issue.
GoliathJeeper
NAXJA Forum User
- Location
- Winnfield, Louisiana
Talyn
NAXJA Forum User
- Location
- Radford, Communistwealth of Virginia
You should have shut it down and found the back firing problem then. Hopefully 1500 RPM was enough to splash the oil around and break the cam in.
I still think you have a timing issue.
I still think you have a timing issue.
wolfpackjeeper
NAXJA Forum User
- Location
- 500' and 500KCAS, RAF lakenheath
Me too, I had a hard time with mine getting it to start and run correctly the first time. I re-indexed the dizzy and it helped. Then I replaced all the grounds and bought a new dizzy and it has ran like a champ since
jeez Talyn, you are a hardhead.
Maybe youre right, I'll tell al the guys I race with we shouldn't be reading plugs..just because that's your way, doesn't mean it's the only way. And I most certainly do have proof..the plugs! I'm not going to go into my whole rationale for using the 30s, I don't owe you anything.. you don't like it, so don't do it.
I'm done crudding up this guys thread with trash. If you must vent, spare the rest of the world and pm me.
Anyhow, seriously Goliath, ck the distributor thing. I know it sounds too simple, but it makes a HUGE diff, and doing it the old school way of lining up #1 with the piston at tdc is actually incorrect on this motor. That will cure the stumble. Then I'd go after the fuel. I don't know anyone with a stroker who isn't running at least a 24# inj.
Maybe youre right, I'll tell al the guys I race with we shouldn't be reading plugs..just because that's your way, doesn't mean it's the only way. And I most certainly do have proof..the plugs! I'm not going to go into my whole rationale for using the 30s, I don't owe you anything.. you don't like it, so don't do it.
I'm done crudding up this guys thread with trash. If you must vent, spare the rest of the world and pm me.
Anyhow, seriously Goliath, ck the distributor thing. I know it sounds too simple, but it makes a HUGE diff, and doing it the old school way of lining up #1 with the piston at tdc is actually incorrect on this motor. That will cure the stumble. Then I'd go after the fuel. I don't know anyone with a stroker who isn't running at least a 24# inj.
Talyn
NAXJA Forum User
- Location
- Radford, Communistwealth of Virginia
And I'm sitting here thinking the same thing of you, fabjunkie. I'm not venting, I'm giving the guy information so he doesn't run the 30# injectors.
Check the coil too.. i don't think it would cause back firing.. but it could cause hesitation.
Check the coil too.. i don't think it would cause back firing.. but it could cause hesitation.
bigdaddyjlove
NAXJA Forum User
- Location
- Atalanta
Still wondering if it has thrown a check engine light. If you can get it to run long enough to drive around a little, you may get a crank sensor/cam sensor disagree ( can't remember the P#) Believe me, i know how you feel. On the third stroker, I would have bet my teeth that I had it right. Try moving the dist one tooth either way and see if it helps. Its easy to try this.
p.s. add an additive to the oil during cam break in. GM Eos or STP are both ZDDP heavy. Not going to beat the dead horse, this has been covered to death.
p.s. add an additive to the oil during cam break in. GM Eos or STP are both ZDDP heavy. Not going to beat the dead horse, this has been covered to death.
Talyn
NAXJA Forum User
- Location
- Radford, Communistwealth of Virginia
I don't think it will throw a code for the cam sensor/crank sensor out of sync. I have seen the cam sensor/distributor installed incorrectly enough and I haven't seen anyone complain of a specific code for it beside misfire codes.
bigdaddyjlove
NAXJA Forum User
- Location
- Atalanta
one of mine threw the code. one didn't (third was a renix) go figure?
GoliathJeeper
NAXJA Forum User
- Location
- Winnfield, Louisiana
okay just a little update and a few questions. now back in louisiana and found my 24# injectors. also picked up a new coil. going back to memphis to get the jeep this weekend and was just wondering about the grounding issue. i know before i looked through the fsm and found all the grounding points that i had a lot of problems with things not working. (fuel pump, coil, etc.) and do you guys think this could be an issue? im convinced now it is a timing issue and partially not getting enough fuel. cant wait to get it back home and start wheeling this thing!
