Muad'Dib 4.7L stroker build

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Re: Muad'Dib 4.7L stroker build

Post by amcinstaller »

if you go that route ms2 is the one you need
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Re: Muad'Dib 4.7L stroker build

Post by SilverXJ »

Two posts in this thread says the Renix PCM doesn't adapt: http://www.jeepstrokers.com/forum/viewt ... 573#p28573
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Re: Muad'Dib 4.7L stroker build

Post by Muad'Dib »

How or why would this benefit me? So that i could use a less expensive solution?

I pulled the computer and it looks clean with nothing burnt... i guess i just need to try a computer.. anyone got one i could try for a 90 MY??? ;)

I tried the whole "grounding" thing the past couple days with no result... although thats what i expected as i thought my grounds were good ( already went through them all before). I even added an extra ground for the 02 and CTS.

Im starting to think that its possible my 02 is randomly going out on me. Its the strangest thing... it will work fine for awhile and then all of the sudden it will be silly. When its acting up the afr's will stay rich (11-12.5) and will try to climb back up to 14.7. As its climbing back, it will just about reach stoich and then drop down rich again... its sooooo weird! Any suggestions on that one?

I finally got myself a Analog meter today so tomorrow i should be able to test the 02, CPS and stator.
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Re: Muad'Dib 4.7L stroker build

Post by yuppiexj »

I have a couple of Renix ECUs. I'll get the part numbers off of them this afternoon and get back to you.

Edited to add IIRC it's from an 88 XJ AT

EF 8953005406
s 101 140 202 B
8816--datecode
Last edited by yuppiexj on March 21st, 2012, 1:29 pm, edited 1 time in total.
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Re: Muad'Dib 4.7L stroker build

Post by Muad'Dib »

Sweet thanks... so far everything is checking out ok; measurements taken directly at the ECU.
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Re: Muad'Dib 4.7L stroker build

Post by Muad'Dib »

Quick update...

My Stroker runs about the same.. Fighting only with weird AFR issues. I still have the lean tip in... and every now and again i have a problem with it staying rich after decel (11ish). I think ive narrowed the rich decel issue down to a faulty 02 sensor or cheapie TPS. I was considering ordering a $140 MOPAR OEM TPS.

Gas mileage in this thing sucks.. i average 10MPG's in town. I do work very close to home though so im sure thats part of the problem. I would really like to get it up to 15MPG's in town... but i just dont see that happening unless my 02 really was having an issue.

Still debating on stepping down with injectors again... Started with 26# which were way to large. Now im running 23# and they are still a bit large. Thinking of 21#ers... we will see if i go that route.


On another note, turns out the plugs i was running from the begining have a gap of .043... but stock is .035. Changed out my plugs with OEM replacements.. so i am back down to .035 although i am a heat range hotter now (back to 5). I have yet to pull them and check them out but only real difference i notice is a slightly smoother idle (Jeep doesnt shake as much as before. BD Motor Mounts dont help).
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Re: Muad'Dib 4.7L stroker build

Post by Muad'Dib »

Another update if anyone is reading this.

The right size plugs seem to be improving my gas mileage and i'm finally to the point to where i am fairly satisfied with the tuning of this thing. I have yet to pull the plugs and check how they are doing with the Hotter plugs. I will do that pretty soon.

Still have the lean tip in.. that is never going away unless i go with a megasquirt set-up. I have accepted that. I did order a factory TPS ($145!!!) and once i get it in the mail i will install it. I will be extremely surprised if it makes a difference.

I do have the right size injectors now.. no need to step down. I am pretty confident i found the sweet spot for tuning this thing. I lowered the fuel pressure to stock, and i upped the MAP voltage. Before i was trying to up the fuel pressure and lower the MAP voltage.. this didn't work as well.

On my first run i did a 0-60 in ~7 Seconds. This was with a lean AFR at about 13.7... i Upped the Map again (currently at 5.25v) and this enriched my AFR @ WOT to 13.1ish. didn't time the 0-60.. but my butt dyno says its an improvement. Maybe cut a second off of everything.
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Re: Muad'Dib 4.7L stroker build

Post by Muad'Dib »

Just a super quick update.

Been hearing what i thought was mild ping, but now its getting worse and making a squeeling sound. It only does this at lower RPM's (probably only hearing it at that time). Im afraid that its possibly a cracked Flexplate.. I opened the inspection cover and cant see any cracks. Seems strange my 1 year old Flexplate has already cracked if thats what it is.

Got a MT2500 off ebay for an excellent price. Hooked it up tonight and its working well. Went for a quick drive and all i can tell so far is that when i decel to lower RPM's i randomly go into Open Loop. I think this is what has been causing my RPM "Jumping" Issue (ive talked about that on NAXJA).
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Re: Muad'Dib 4.7L stroker build

Post by Muad'Dib »

Looks like im going to be pulling the transmission and replacing a 1 year old flexplate.

As far as the lean tip-in, still have that issue also.

Can anyone help me make since of my short term fuel trims? Im trying to figure out if my injectors are too small or just right. Long term stays at 128 always.. but short term seems to jump all over the place.
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Re: Muad'Dib 4.7L stroker build

Post by SilverXJ »

128? What is that?

I am not sure if renix actually uses fuel trims.
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Re: Muad'Dib 4.7L stroker build

Post by MrNoBody »

Hello, I have read thru all 17 pages of this thread; I do not normally post, I am just a lurker! :geek:

In any event, I have the following input:
IF: IAT is located any place other than Intake Manifold
Then: The PCM fuel/timing map will be off
AND: This out of range may cause your irregular spark plug color
OR: This out of range may cause a ping, ring, ding that will trigger your knock sensor which may cause your irregular spark plug color
Spark plugs with that hue and level of saturation mostly point to ignition events.
With regard to throttle body: you are running a reversed nozzle and have impacted the velocity of flow into motor that mathematically is impractical given the stock valves, and small cam profile - you have lost scavenging; thus, losing top end; again cam power range.
Best way to check grounds is to use meter and measure resistance at furthest distance and from ground connection in question - resistance should not be more than the conductivity of the material versus the distance; otherwise, ground connection is faulty. Does intake have ground with that coating at sensors?
Further, noise in electrical system created by ground loop can cause wide band readout to randomly display values that are responding to electrical noise.
Lastly, what is your quench height and you do realize that the increase stroke increases piston speed which causes rapid breathing; therefore, requiring higher velocity to scavenge air - get a 4in diameter 2ft long pipe stick it in bucket of water and use your mouth to draw water; conversely, try the same procedure with a 1in diameter 2ft long pipe. What did you find? Now try it at a more rapid rate of respiration. What did you find? USE CAUTION WHEN PERFORMING THIS PROCEDURE AND BY TRYING THE AFOREMENTIONED TEST YOU RELEASE ME OF ALL LIABILITY AND ENTER INTO SAID EXERCISE AT YOUR OWN RISK.

I look forward to your posted updates and will respond at my convenience (when I have time). Great work for your first build and I applaud those who have assisted!
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Re: Muad'Dib 4.7L stroker build

Post by Muad'Dib »

SilverXJ wrote:128? What is that?

I am not sure if renix actually uses fuel trims.
Yeah i think it does.. otherwise i wouldnt be able to read that data with the mt2500.
If it feels right, then STROKE it!
You're lucky that hundred shot of CAPS LOCK didn't blow the welds on the forum!!
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Re: Muad'Dib 4.7L stroker build

Post by Muad'Dib »

MrNoBody wrote:Hello, I have read thru all 17 pages of this thread; I do not normally post, I am just a lurker! :geek:

In any event, I have the following input:
IF: IAT is located any place other than Intake Manifold
Then: The PCM fuel/timing map will be off
AND: This out of range may cause your irregular spark plug color
OR: This out of range may cause a ping, ring, ding that will trigger your knock sensor which may cause your irregular spark plug color
Spark plugs with that hue and level of saturation mostly point to ignition events.
With regard to throttle body: you are running a reversed nozzle and have impacted the velocity of flow into motor that mathematically is impractical given the stock valves, and small cam profile - you have lost scavenging; thus, losing top end; again cam power range.
Best way to check grounds is to use meter and measure resistance at furthest distance and from ground connection in question - resistance should not be more than the conductivity of the material versus the distance; otherwise, ground connection is faulty. Does intake have ground with that coating at sensors?
Further, noise in electrical system created by ground loop can cause wide band readout to randomly display values that are responding to electrical noise.
Lastly, what is your quench height and you do realize that the increase stroke increases piston speed which causes rapid breathing; therefore, requiring higher velocity to scavenge air - get a 4in diameter 2ft long pipe stick it in bucket of water and use your mouth to draw water; conversely, try the same procedure with a 1in diameter 2ft long pipe. What did you find? Now try it at a more rapid rate of respiration. What did you find? USE CAUTION WHEN PERFORMING THIS PROCEDURE AND BY TRYING THE AFOREMENTIONED TEST YOU RELEASE ME OF ALL LIABILITY AND ENTER INTO SAID EXERCISE AT YOUR OWN RISK.

I look forward to your posted updates and will respond at my convenience (when I have time). Great work for your first build and I applaud those who have assisted!
I will try to respond to your questions as asked although your post is a bit bunched so if i missed something please bare with me.

Ive thought about the IAT being relocated causing issues with the computer. I have a feeling at worst case it would just cause the computer to fault defaulting it into open loop.. which is what i experience sometimes. Otherwise i think all that happens to the timing is advancing it. I havent had a problem with pinkish colored spark plugs since i gapped them correctly. The ones i snapped pics of were gapped at .045 and i didnt realise it. Checked knock values with MT2500 and everything is normal. 0 at idle and doesnt start jumping up to 10ish until 2000 RPM's Ive seen it jump to 30ish at WOT blips. Apparently anything below 100 is ok.

Are you thinking that the throttle body is causing loss of high end power due to the size of the TB opening. Its only 68mm and the recommended for a stroker is a larger bore of like 62-63mm which ends up being only about 1/8th inch larger.

As far as grounds go.. i am 99.99999% sure that i dont have grounding issues. Almost all my sensors have ground splices directly to the block and everything reads less than 1 ohm to the battery; measured both at the ground connector and the ECU.

My quench height is my HG Compressed thickness... .044.
If it feels right, then STROKE it!
You're lucky that hundred shot of CAPS LOCK didn't blow the welds on the forum!!
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Re: Muad'Dib 4.7L stroker build

Post by MrNoBody »

Muad'Dib wrote:
MrNoBody wrote:Hello, I have read thru all 17 pages of this thread; I do not normally post, I am just a lurker! :geek:

In any event, I have the following input:
IF: IAT is located any place other than Intake Manifold
Then: The PCM fuel/timing map will be off
AND: This out of range may cause your irregular spark plug color
OR: This out of range may cause a ping, ring, ding that will trigger your knock sensor which may cause your irregular spark plug color
Spark plugs with that hue and level of saturation mostly point to ignition events.
With regard to throttle body: you are running a reversed nozzle and have impacted the velocity of flow into motor that mathematically is impractical given the stock valves, and small cam profile - you have lost scavenging; thus, losing top end; again cam power range.
Best way to check grounds is to use meter and measure resistance at furthest distance and from ground connection in question - resistance should not be more than the conductivity of the material versus the distance; otherwise, ground connection is faulty. Does intake have ground with that coating at sensors?
Further, noise in electrical system created by ground loop can cause wide band readout to randomly display values that are responding to electrical noise.
Lastly, what is your quench height and you do realize that the increase stroke increases piston speed which causes rapid breathing; therefore, requiring higher velocity to scavenge air - get a 4in diameter 2ft long pipe stick it in bucket of water and use your mouth to draw water; conversely, try the same procedure with a 1in diameter 2ft long pipe. What did you find? Now try it at a more rapid rate of respiration. What did you find? USE CAUTION WHEN PERFORMING THIS PROCEDURE AND BY TRYING THE AFOREMENTIONED TEST YOU RELEASE ME OF ALL LIABILITY AND ENTER INTO SAID EXERCISE AT YOUR OWN RISK.

I look forward to your posted updates and will respond at my convenience (when I have time). Great work for your first build and I applaud those who have assisted!
I will try to respond to your questions as asked although your post is a bit bunched so if i missed something please bare with me.

Ive thought about the IAT being relocated causing issues with the computer. I have a feeling at worst case it would just cause the computer to fault defaulting it into open loop.. which is what i experience sometimes. Otherwise i think all that happens to the timing is advancing it. I havent had a problem with pinkish colored spark plugs since i gapped them correctly. The ones i snapped pics of were gapped at .045 and i didnt realise it. Checked knock values with MT2500 and everything is normal. 0 at idle and doesnt start jumping up to 10ish until 2000 RPM's Ive seen it jump to 30ish at WOT blips. Apparently anything below 100 is ok.

Are you thinking that the throttle body is causing loss of high end power due to the size of the TB opening. Its only 68mm and the recommended for a stroker is a larger bore of like 62-63mm which ends up being only about 1/8th inch larger.

As far as grounds go.. i am 99.99999% sure that i dont have grounding issues. Almost all my sensors have ground splices directly to the block and everything reads less than 1 ohm to the battery; measured both at the ground connector and the ECU.

My quench height is my HG Compressed thickness... .044.
My apologies for the bunching of text!

I am not sure what the numerical value is you are seeing with the snap-on meter as I have never used one. I do know however, that the pcm uses voltage generated from the knock sensor(piezo) to retard total timing to reduce detonation. To test the value you elaborated, try 87octane fuel, record values, then once that is run out, try 93octane and record values. Lastly compare your documentation.

The rule of thumb is more air in, the more power created; however, that is not entirely true as the velocity of the air in has an effect too as does the soundwave created by the opening and closing of the valve itself. The air rides this 'wave' both in and out of the motor at the throttle body(larger throttle body lets more air out). This is also true on the exhaust side of the motor. Needless to say, I will apologize now as the last two statements have been shortened as the complete wave analysis would take a considerable amount of time for me to specifically state with great detail. I personally would use the smaller throttle body unless you used forced induction.

So you are one in one hundred thousandths unsure? J/K That resistance seems ok. To prevent ground loops, all the grounds should ground to the same location; unless the wire would have to be exceptionally long where the object would be impacted by the velocity of the electrons given its(the objects) electron requirements. For example: Some audio amplifiers require large amounts of current(electrons) and you would want the shortest ground wire length possible for said amplifier due to this current requirement. Again I apologize for short statement as the complete analysis would take a considerable amount of time to specifically state with great detail. In any event, the multiple ground points you may see under the dash of the vehicle are all based on the total current required for the circuits and I would use one of those ground points for any added accessories. The same for under the hood. I perceive "...ground splices..." as non-soldered connections/connectors. Crimped connectors wobble which causes noise. I would solder all connections/connectors, make sure all ground points are free of corrosion, dirt, grease and apply Dielectric Grease.

That quench height is good although given the design of the piston I might have left it five to ten thousandths in the hole for stability. If the piston was a flat top then I would say differently. Having said that, I have thought about machining the flat of the piston to match the dish vs machining the dish deeper; although some finite element analysis would probably be beneficial before doing such plus reshaping the combustion chamber hemispherical. Not sure head has enough material and I haven't put enough into it to elaborate further.
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Re: Muad'Dib 4.7L stroker build

Post by Muad'Dib »

Muad'Dib wrote:Looks like im going to be pulling the transmission and replacing a 1 year old flexplate.

As far as the lean tip-in, still have that issue also.

Can anyone help me make since of my short term fuel trims? Im trying to figure out if my injectors are too small or just right. Long term stays at 128 always.. but short term seems to jump all over the place.

Turns out the noise's i was hearing was a very bad ujoint in the rear driveline. Two new ujoints later and the noise is gone. Plus the drive is much smoother.

It started as what i thought was light ping, then started to get nastier and started squeaking. Could have swore it was coming from right below my feet.

I think i have a bad CPS as the Jeep sometimes will just randomly die. Although it always starts right back up. I want to say that one time it didnt start back up right away (took about a minute or so). This has happened a total of about 5 times. IM wondering it this weak CPS signal is causing some of my issues with lean tip and randomly going into open loop (verified with mt2500 and 02 reads very rich). CPS replacement is next.
If it feels right, then STROKE it!
You're lucky that hundred shot of CAPS LOCK didn't blow the welds on the forum!!
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