New stroker feels underpowered

[Cheromaniac]

I read on Dino's site that the ideal AFR for fuel economy is around 15.5-16.3.

That's during light throttle cruising. The AFR during warm idle should be 14.7:1.

[Comanche91]

I have put a timing light on many OBDI Xj's and they all seem to run at about 12-14*btdc at idle. Also check what your total advance is at about 2.5-3k rpm. Should be about 32-36* Good luck.

I agree 100% with that. Have you checked the timing with a light? Not only should it read 12-14 * BTDC, but it should be nice and steady, not jumping around. If it's not steady, pull the distributor and check for slop in the shaft. Could be something as simple as new bearings or replacing it with a less worn dizzy.

[brokenaxle]

So I installed fresh 0280155715 24lb/hr injectors and the hesco high pressure fuel regulator. I drained the tank and put some fresh 91 octane in it because the engine started to ping from the old fuel. The pinging has stopped, the backfiring has also stopped and the afr around idle is closer to 14.7. However, the engine developed a new problem. It started to idle really low once warmed up, around 400 rpm, and would die if I did not give it gas. I replaced the IAC and TPS and the problem went away for about 30 miles, but now it's back. When the rpm drops really low the AFR also turns very rich, around 11:1. When I bought the new IAC at the dealer the guy dropped it on the counter from about 8 inches in the air, but he assured me it would be fine--could he have damaged/broken it when he did this? The TPS is aftermarket and made by Delphi, not sure if that is a decent part. The MAP is also a new Delphi unit. The cam does seem bigger than I would like--the power isn't really there until I hit 2400 rpm or so--could this mess with the ecu resulting in a low idle? Any ideas on what could make the idle rpm low, the afr high at idle, and the engine die at idle if I don't push on the accelerator?

[Spliffotticle]

I have to pull my battery and short the pos to neg to discharge the computer's temp memory that it has to learn things. Then it starts out default and learns as it adjusts with knock sensing o2 & so forth the way a trans computer learns your ideal shifting patterns. Reset the ol lady's liberty... whole new animal. So higher octane means it needs to learn to spark on a different curve & different times on a different dwell for different conditions but can only adjust in small increments overall so you need to start from default. Not all vehicles do this so I'd do that before troubleshooting further so you can eliminate a simple thing. Also.... why are you running 91? is your dynamic cr that high? or are you turbocharged?

[dragginwagon406]

How did this end up working out?

[brokenaxle]

So apparently the fuel pickup fell off inside the tank and the pump was sucking air intermittently...boy that took way too long and too much money to figure out! I put 91 in there just to make sure it doesn't ping anymore during break-in with the old gas that had been in there. It runs better now, although I kinda wish I went with a smaller cam (the power band is a bit high in the rpm for general offroading imo, but should be good for mudding). It still seems to be running too warm, I installed a new 3-row aluminum Champion radiator, 195 high flow thermostat, and new flowkooler water pump (I flushed the system and all the loose rust from sitting so long made the old water pump start to squeal). At idle it's right at 210, but under load and at higher rpm's (on the freeway for example) my temp gauge reads about 230. The sending unit is in the stock location on the back of the head, but this should still read around 210 right? I will be installing an oil cooler next unless anyone suggests otherwise. On another note I think I will be swapping my 4.56's for some 5.38's, with my 35's the speedo is accurate for the first time ever but I just don't see myself going above 70 or 75 in it.

[SilverXJ]

It should be around 210*. An oil cooler will most likely not help. If it helped any you would be simply be band-aiding the original cooling issue. You have no idea what your actual oil temp and you will most likely be heating the oil up actually. I had a cooling problem similar to yours. Hot under load especially on the highway. I removed the high flow FlowKooler water pump and never had the problem again. From what I found water cam move too fast through the rad, not providing proper heat transfer.

[lafrad]

the 5.38's will fix your issues with the cam... LOL.

A big cam changes the *actual* VE's of the engine. low PRM VE's will fall considerably, and high RPM VE's will increase considerably... and it sounds like the "crossover" point will be the 2000-2500 rpm are.

That will cause a computer like ours to run "RICH" in low RPM (its fueling for VE that it is estimating to be higher than it actually is) and "Lean" at high RPM (the reverse of the low)...

You need to get yourself a programmable adjustable map sensor... lean it out in the low RPM, richen it up in the high RPM.

[doublins]

Any suggestions on a ¨programmable adjustable map sensor?¨ I´d like to be able to alter my fuel map as well, but don´t know where to start.

-C

[lafrad]

http://www.splitsec.com/products/calibrators2.htm

this is what I use.

works *perfectly* for all fueling changes.

Hook it up so you have a tach input and a map input. then your output signal goes to the map sensor.

I don't have a howto written up yet, I'll see if I can take pictures and get a brief guide written up in the next week or two.

[lafrad]

http://www.splitsec.com/products/psc1/PSC1003.htm

thats the one, in particular.

[montelibre]

I bought the Split second FTC1-019B (fuel and timing calibrator), but I have not intalled yet.
http://www.splitsec.com/products/fuel-t ... brator.htm

[doublins]

Oh, cool- I actually had been looking at a couple of the split-second units a couple of months back, but I think I´d need to get a wideband installed before I can actually program it, no?

[Cheromaniac]

Yup. A wideband would be preferable so you can map the AFRs across the rpm range under WOT and make your adjustments accordingly to achieve a "flatline" 13.0:1 AFR.