Stroker sounds tight, runs rough HELP

Post by **Swampbilly21** » July 2nd, 2012, 3:33 am

Ok Ive looked at a couple of threads and cant seem to find anyone with my problem. I have a 1989 jeep comanche, with a stroker motor that I've built. Heres a little background: I used a 1997 4.0 block from a grand cherokee, disassembled the motor and rebuilt it with all new parts for the most part. I used a remanufactured 1989 4.2 liter crank, crane cam, rebuilt oil pump, new chain, new lifters new push rods, cylinders bored.20 over, new .20 over hypereutic pistons,did a valve lap job, obviously new main and rod bearings. everything has been adapted to the new HO block. the throttle positioning sensor has been adapted to the h o throttle body, the idle air control has the plunger from a 97 4.0 throttle body, and a new knock sensor has been installed, the crankshaft positioning sensor is plugged in, that map sensor has been plugged into the throtle body, I also have a voltage regulator on the firewall managing the voltage for the map sensor, ( it is currently at 5.3 volts) it has a new distributor new cap new rotor and new spark plug wires, the o 2 sensor is plugged in I'm not sure if it's working properly. the injectors that I use are from a 5.7 liter v 8 magnum from a dodge, from my understanding these flow at 24 pounds an hour. so my issue is I start the motor and it will run until the computer calculates the engines performance and then it will start to run rough at a very low idle and then stall. I'm beating my head against the wall here. has anyone run into this problem before? I may have missed a few mods or parts, so you may inquire if I missed anything and I will clarify those things. HELP!

Post by **Swampbilly21** » July 2nd, 2012, 3:33 am

Ok Ive looked at a couple of threads and cant seem to find anyone with my problem. I have a 1989 jeep comanche, with a stroker motor that I've built. Heres a little background: I used a 1997 4.0 block from a grand cherokee, disassembled the motor and rebuilt it with all new parts for the most part. I used a remanufactured 1989 4.2 liter crank, crane cam, rebuilt oil pump, new chain, new lifters new push rods, cylinders bored.20 over, new .20 over hypereutic pistons,did a valve lap job, obviously new main and rod bearings. everything has been adapted to the new HO block. the throttle positioning sensor has been adapted to the h o throttle body, the idle air control has the plunger from a 97 4.0 throttle body, and a new knock sensor has been installed, the crankshaft positioning sensor is plugged in, that map sensor has been plugged into the throtle body, I also have a voltage regulator on the firewall managing the voltage for the map sensor, ( it is currently at 5.3 volts) it has a new distributor new cap new rotor and new spark plug wires, the o 2 sensor is plugged in I'm not sure if it's working properly. the injectors that I use are from a 5.7 liter v 8 magnum from a dodge, from my understanding these flow at 24 pounds an hour. so my issue is I start the motor and it will run until the computer calculates the engines performance and then it will start to run rough at a very low idle and then stall. I'm beating my head against the wall here. has anyone run into this problem before? I may have missed a few mods or parts, so you may inquire if I missed anything and I will clarify those things. HELP!

Post by **Swampbilly21** » July 2nd, 2012, 3:35 am

Oh and I cut the ears off the distributor as to have the ability to retard or advance the timing as well. My next step is to probably wire in an air/fuel mixture guage and see what it tells me about my exhaust. Tested the o2 sensor today, 5.0 volts constant wen started it drops down to .6 IF the engine runs long enough. Checked voltage on tps and adjusted arm to specs: greater than 200 millivolts closed and at about 4.3 @ WOT. Install an air/fuel mixture guage today reads rich constantly..attempted voltage change on MAP voltage regulator: no change. It has to be a sensor or controller issue because it will idle fine and then idle rough, then surge then stall. But the stall isnt so much a slow stall but immediate. }:0

Post by **cruiser54** » July 2nd, 2012, 5:02 am

I would take the MAP adjuster off for now just for diagnosis purposes. MAP, CTS, and IAT are the biggest players in a rich mixture as far as sensors go.

I'm attaching some TPS adjusting procedures below. Use the flat 3 wire connector for your adjustment.

Did you get all the little ground wires on at the engine dipstick tube stud and do they have a shiny metal surface under them?

And BTW, rotating the distributoe doesn't realy adjust timing. It can cause rough running issues though as the spark has to jump real far from the rotor to the cap as the eCU fires the coil. You need to index your distributor properly.

RENIX TPS ADJUSTMENT

Before attempting to adjust your TPS be sure the throttle body has been recently cleaned. It's especially important that the edges of the throttle butterfly are free of any carbon build-up.

IMPORTANT NOTE: With the Key OFF, and using the positive (red) lead of your ohmmeter, probe the B terminal of the flat 3 wire connector of the TPS. The letters are embossed on the connector itself. Touch the black lead of your meter to the negative battery post. Wiggle the wiring harness where it parallels the valve cover and also over near the MAP sensor on the firewall. If you see more than 1 ohm of resistance, or fluctuation in your ohms reading, some modifications to the sensor ground harness will be necessary. The harness repair must be performed before proceeding. I can provide an instruction sheet for that if needed.

MANUAL TRANSMISSION:
RENIX manual transmission equipped XJs have a three-wire TPS mounted on the throttle body. This manual transmission vehicle TPS provides data input to the ECU. The manual transmission TPS has three wires in the connector and they're clearly embossed with the letters A, B, and C. Wire "A" is positive. Wire "B" is ground. Key ON, measure voltage from "A" positive to "B" ground by back-probing the connectors. Note the voltage reading--this is your REFERENCE voltage. Key ON, back-probe the connector at wires "B" and "C". Measure the voltage. This is your OUTPUT voltage. Your OUTPUT voltage needs to be seventeen percent of your REFERENCE voltage. For example: 4.82 volts X .17=.82 volts. Adjust the TPS until you
have achieved this percentage. If you can't achieve the correct output voltage replace the TPS and start over.

AUTOMATIC TRANSMISSION: RENIX automatic transmission equipped XJs have a TPS with two connectors. There is a flat three-wire connector, same as the manual transmission vehicles have, and it is tested the same as the manual transmission equipped vehicles—FOR ENGINE MANAGEMENT RELATED ISSUES.

However, the automatic TPS also has a square four-wire connector clearly embossed with the letters A,B,C, and D. It only uses three wires and provides information to the Transmission Control Module. Key ON, measure voltage between "A" positive and "D" ground. Note the voltage. This is your REFERENCE voltage. Back-probe the connector at wires "B" and "D". Measure the voltage. This is your OUTPUT voltage. Your OUTPUT voltage needs to be eighty-three percent of your REFERENCE voltage. For example 4.8 volts X .83=3.98 volts. Adjust the TPS until you have achieved this percentage. If you can't, replace the TPS and start over. So, if you have an automatic equipped XJ your TPS has two sides--one side feeds the ECU, and the other side feeds the TCU.
FOR AUTOMATIC TRANSMISSION RELATED ISSUES. Check the four-wire connector side of the TPS.
If you have ENGINE issues check the three-wire connector side of the TPS. For those with a MANUAL TRANSMISSION--the TPS for the manual transmission XJs is stupid expensive. You can substitute the automatic transmission TPS which is reasonably priced.
Revised 05-28-2012

Post by **Swampbilly21** » July 2nd, 2012, 5:44 am

Yes. I replace my leads with new ones. I ran the negative from the battery to the block @ the dipstick along with the 2 eyelets shiny clean. And then ground strap from back of head to firewall nice and clean and 2 eyelets as well on the drivers side fender. I did notice a long single red wire with a black spade connector coming out of the harness on the passenger side. Do u know where this goes?

Post by **Swampbilly21** » July 2nd, 2012, 6:24 am

And the red wire is hot btw my idiot self didnt even check if it was hot via the ignition or constant

Post by **cruiser54** » July 2nd, 2012, 2:36 pm

The wire you're referring to is probably to the underhood light. Have you checked your sensor ground circuit per the write-up? How about adjusting the TPS?

Post by **Swampbilly21** » July 2nd, 2012, 2:41 pm

No I havent yet....just got out of work. And I do not have an underhood light. Standard harness I guess.

Post by **Swampbilly21** » July 2nd, 2012, 4:34 pm

Alright i performed the ohm test for the wire harness and found no higher reading than .8 so there is no reason to do a ground relo for the TPS. Now i tested the TPS input voltage and came out with 4.7 volts and the output at .1. 4.7x.17=7.99. adjusted my TPS to .800. Started vehicle. Ran ALOT smoother. Then after a glorious 20 seconds of bliss....and immediate shut down of the motor. I definitely like the way it sounds now though. What about the CTS? Or rather, whats next?

Post by **wjtom** » July 2nd, 2012, 6:07 pm

probably a stupid question but you keep talking about starting the motor and idling,did you break in the camshaft?run it at 2000 plus rpm for 30 minutes?

Post by **wjtom** » July 2nd, 2012, 6:09 pm

also if you keep the idle up manually will it keep running.just hold your foot on the gas a little?

Post by **Swampbilly21** » July 2nd, 2012, 6:18 pm

omg...sonofamonkeys uncle screw me sideways with a chainsaw. i completely forgot.

i have been so meticulous about how i performed the rebuild and tottally blew it by not remembering to break in the cam

would that really be causing my problem?

Post by **Swampbilly21** » July 2nd, 2012, 6:19 pm

wjtom wrote:also if you keep the idle up manually will it keep running.just hold your foot on the gas a little?

yes it stays running great wen i apply throttle.....

Post by **cruiser54** » July 2nd, 2012, 6:39 pm

Maybe you better break in the cam first and we'll figger out the idle stuff later. You need to get the distributor indexed properly before proceeding after cam break-in.

Post by **Swampbilly21** » July 2nd, 2012, 6:45 pm

10-4 after work tomorrow i will break in the cam as per procedure and get back to you. thanks for all the help. talk with you tomorrow.