New stroker feels underpowered

[brokenaxle]

I swapped a stroker into my CJ7 and have been driving it around town to break it in. The first thing I noticed when I drove it was that it is not delivering the power and torque I expected from the motor, and it pops/backfires out the exhaust when I let off the throttle suddenly...granted it has less than 100 miles on it so everything should still be tight, but still I would expect more power (It feels slightly more powerful than the 4.2). It was starting and running fine otherwise, until today when the engine died on me several times and then did not want to start for about a minute (it would catch then die immediately). When I got it started again I had trouble with the engine continuing to die as I drove it home. I am getting no codes from the MIL. I had a shop do the wiring with a Hesco harness, and they said that the timing is good...the CPS is mounted on a 2003 Wrangler bellhousing and not on the dampener btw. I hooked up a timing light and can see that the timing is about 8 degress BTDC at idle, and the engine misses occasionally at idle but I suppose this could be attributed to the cam (Crane truck cam, I can dig up and post the stats for it if necessary). The ears have been trimmed off the distributor. Fuel pressure is good. Oil pressure is good, around 40 psi although it was lower before I changed the oil and filter. My temp gauge is not working, not good to be breaking in an engine with no temp reading I know but I am ordering a new gauge tonight. I am running 91 octane fuel for the break-in, and about 1/3 of the gas in the tank was treated with Sta-Bil quite a while ago...the rest is fresh. Here are the specs and components I am running:

-Block bored .030 and decked .030 with mopar performance head gasket
-Rebuilt head
-4.2 serpentine crank, turned, with refurbished 4.2 rods and ARP bolts
-KB Silvolite pistons dished .040, CR~9.2
-Crane Cams Truck Cam
-2001 intake manifold
-Renix-style spark plugs per the advice of Benny at Hesco
-Ford 24# injectors, part number F55E-A2E, purchased used on ebay
-Hesco high pressure adjustable fuel pressure regulator (new)
-All new sensors
-Cloyes double roller timing set
-Flow Kooler water pump
-Flex-a-lite dual fans
-Hesco M/T ECU (new)
-Hesco wiring harness with CPS mounted on the bell housing (bell housing and transmission are from a 2003 Wrangler, NV3550)
-New catalytic converter with Magnaflow muffler
-New poly tank and new fuel lines

I hooked up an aftermarket tach today to the gray wire coming off the coil. One thing I observed using a multi-meter was that the gray wire has voltage even when the ignition switch is turned off. Is this normal? The tach seems to be working fine, and the motor idles around 900 at first then settles down to about 600-700. Does it sound like a timing issue? A bad sensor even though they all are new? I appreciate any and all help, this Jeep has been in pieces for 5 years and I am dying to finish it.

[brokenaxle]

I did some searching and didn't come up with any answers...I hate to be the new guy who's first thread is one like this, but I'm stumped and the shop that did the wiring is not offering any solutions. Thanks in advance to anyone who points me in the right direction.

[minagera]

Do you have any Air Fuel gauge readings, or more specifically a wideband reading?

It might be all the fuel being off.

[4.whoa]

I swapped a stroker into my CJ7 and have been driving it around town to break it in.

You did break the cam in 1st,right

I've heard that a bad cam lobe will make an engine pop like that but i've never had it happen.

[Cheromaniac]

Does it sound like a timing issue?

No but it could possibly be a distributor indexing issue. This page from my site will help you get it set right:

http://www.angelfire.com/my/fan/dist_index.html

[YJason]

Distributor index was the first thing that came to my mind. Second thought is water in the gas.

[brokenaxle]

I don't have a wideband O2 sensor, but if I can't figure this out soon I may invest in one. The shop that did the wiring said they broke in the cam for me, so hopefully that is not the issue. I'll try reindexing the distributor tonight after work...I'm wondering if cutting the ears off the distributor was a bad idea, but I'll mess around with it and see what happens.

[stege123]

Hi

IMHO no physical damage done, but 5 possibilities.
* Clogged Cat.
* Wrong cam, or wrong timing (easy to check with valve cover removed)
* Fuel starvasion (can give backfiring, and popping sounds)
* To much fuel (sluggish engine, and during Acceleration black smoke)
* Ignition timing off. My experience is that these engines like 12 degrees advance (idle and NO Vacuum) and a max. advance of 34 to 36 degrees. Does your distributor have a vacuum advance?? If yes, remove the hose and check your timing again. The vacuum signal should be "Ported", ie no vacuum signal when idling, vacuum present when revs are more than idling.

I hope my suggestions brings this engine on the right track. I once built a Hesco engine, and it ran monster (until my wife destroyed it (yes, still married))

[BADASYJ]

I would be suspect of the dist moving on you. With no ears it can walk on you. These things will not run if the dist is moved just slightly from the proper place. Check your hold down bolt, just don't snap it off in the block when tightning.

[6TIME]

I did some searching and didn't come up with any answers...I hate to be the new guy who's first thread is one like this, but I'm stumped and the shop that did the wiring is not offering any solutions. Thanks in advance to anyone who points me in the right direction.

Was the cam degreed and installed straight up? Are you using OBDI? If you are at 8*btdc at idle, I would first suspect the dizzy not indexed and/or the cam not degreed properly. I had this issue with my rig starting out. They WILL run one tooth off... just not quite right. Also inspect the rubber ring on the Damper for deterioration or slippage that would cause a skewed timing readings. 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.

[FOXxX]

My first reaction when I read your post was fuel issue. Read my post - "Starting Issue" and see if any of that is related. If you are backfiring that usually means rich AFRs... Im learning too!

[brokenaxle]

No vacuum advance, the damper is new and looks good, and it's OBDI. I turned the engine to TDC and the rotor was pointing at/just before the #1 terminal, about 1.5-2cm from the edge of the cam sensor plug. I moved the distributor over a tooth, and the rotor pointed about 3.5-4cm past the edge of the cam sensor plug. I then rotated the distributor so the rotor pointed exactly 3cm past the edge of the cam sensor plug as suggested in Dino's writeup. The timing light shows the timing to still be around 8 degrees BTDC or even a little less. I took it for a drive around the block; the power feels a little better but it still doesn't accelerate like I would expect it to. It idles just fine, but when I put in the clutch and stomp on the accelerator the engine hesitates for a second before it revs. This only happens when I really put on the gas/at WOT, not when I ease into it. I pulled a couple spark plugs and they were whitish to slightly tan, I can't tell if they are normal or if they were getting too hot like the AFR is too lean. Would it be a bad idea to widen the holes on the CPS and move it to advance the timing? I sure hope the cam is installed correctly. Would clearing the ECU change anything?

[Cheromaniac]

Indexing the distributor has no effect on ignition timing, but you can advance the timing by slotting the CPS bolt holes and moving the CPS closer to the Jeep's centerline (upwards).
You could try clearing the ECU and see if the engine runs better, but the color of your plugs does suggest that the engine's running too lean and that may be the reason for the slight hesitation and lack of power.

[brokenaxle]

I installed a wideband O2 sensor and AFR gauge by AEM. The reading was around 14.5-15 at idle, and pretty erratic when accelerating quickly. I swapped in the stock fuel pressure regulator and now the gauge reads around 14.8-15.5 at idle, and is just as erratic when accelerating. It also reads around 13.8 when engine breaking downhill. I read on Dino's site that the ideal AFR for fuel economy is around 15.5-16.3. Is my stroker running too rich? Is there anything I can do to lean it out besides adjusting the MAP voltage?

[gradon]

Your stroker is not running rich but a tad lean(but you get better economy): 14.7:1 is what most vehicles run at warm idle and closed loop/<~70% throttle. Cold idle would be richer and be in the low 13s, full throttle would be in the high 12s for best power. The only time you would see mid 15s and up would be when you let off the throttle.