89 xj stroker swap

Let me start by saying this is my first post so bear with me if its in the wrong place or full of newbness.


Ok, My 89 Xj had a tired 4.0, and one day she started knocking and it as progressively getting louder so I ordered a 4.7L stroker and swapped it in.
I had my renix TB bored to 60mm and upgraded to 24lb Ford injectors. These were the only changes i made. I replaced all hoses, wires, cap, rotor, thermostat, water pump, and spark plugs. I hooked everything up the way it was, with the exception of the vapor canister. I replaced the fuel filter and added a K&N air element. I had to make a spacer for the nose of the crank as the new stroker crankshaft was longer in this area. Everything went back together nicely and to my liking. I used Valvoline VR1 for the zinc properties and added a bottle of Lucas zinc additave for the cam. Upon startup she ran very rough and erratic, surging up and down but it smoothed out enough to hold at 2800 for 20mins as reccomended by the builder. In this 20 mins my cat began to glow orange melting my carpet in the rear floor area. Not knowing if the cat was plugged up I cut out the cat and replaced it with pipe. The rest of the exhaust is stock and in good shape. After this break in run I double checked timing and all vaccum hoses and could find nothing wrong. I took voltage readings at TPS and o2 sensors and they seem to be within specs that I have. Map is hooked up and working as well. The engine starts and idles decent but as soon as throttle is given it begins to run rough and pop. I checked the knock sensor and while installing the engine I broke the housing on the sensor, so I replaced that also thinking perhaps that wasnt letting the ecm advance timing. But this was no help. I have read and was told that the renix computer would be able to accomodate my larger TB and injectors but it seems like its either not getting the fuel or the timing isnt being controlled correctly.

Ive read up on adjustable Maps and other things but from the sound of those modifications I have something more drastic going on. I was thinking about grinding the dist. to allow adjustment but want to get some input here first. Please feel free to offer advise or ask for more information. I love my xj and am determined to see this beast purr
Sorry for the long post but Im trying to be complete.

Thanks,
Ω

Did you check the Crank Position Sensor? My 89 did the minus the cat. My exhaust melted my wire and after it heated up the wires arc out and started surging really bad like it wasnt getting any fuel or spark took me a while to find the problem. Just a thought

rockcrusher said:

Did you check the Crank Position Sensor? My 89 did the minus the cat. My exhaust melted my wire and after it heated up the wires arc out and started surging really bad like it wasnt getting any fuel or spark took me a while to find the problem. Just a thought

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Im going to go thru everything again and Ill check that for sure, thanks for the ideas. I need em

how much was ur stroker

The cat running too hot can be cause by a plugged cat or an upstream vacuum leak. Depending on the location of the vacuum leak, it can screw with the O2 sensor causing wierd idle/run.

Ok, any more ideas?? Give something to read at least lol Im lost here.

Are you sure that the dist. is indexed correctly...... be out a couple *. Sounds dumb but are you sure the plug wires are in the correct position between the cap and cylinders. Sounds like a spark issue over a sensor issue to me. Good luck.

I have seen a few different ways to install the dizzy. I used one I found elswhere on this forum. What is the correct way?

the "toothpick" method works the best, took all of the guesswork out of that whole situation when building my stroker.

i used an easy-out in a tap t-handle instead of a toothpick, it was the perfect thickness, and didn't allow for any slop

there are alignment holes on the plastic ring below the cam position sensor, and a matching hole in the housing (i am going from my '99, i haven't had my '89 apart this much) there are two holes, one for the 4 cyl, and one for the 6 cyl the one on the edge of the pulse ring is for the 6 cyl. stick a drift, or tap, or toothpick in that hole, and re-install when cyl 1 is at TDC compression (take the plug out to feel for compression, and use the mark on the harmonic balancer and the timing marks on the timing cover) make sure your oil pump is oriented correctly too

i have a pic, but it is from the FSM

i think it is really weird that your cat heated up so much during your initial run. When you cut it out how did it look? Was it being blocked or was the element bad inside of it? A lean mixture would acount for some of the heat, and a blocked cat would make the engine run poorly, but taking out the cat and it not fixing any of your stated problems seems strange.

I found a pic of these holes on this forum but my dist. does not have these. What i did to install it was basically to put #1 cylinder on TDC (finger in spark plug hole to verify compression stroke and mark at zero on timing cover) and have the housing clocked so that the place where the wires exit is at 6 o clock. Line up rotor at 3 o clock and drop in making the rotor end up at 5 o clock. I found this method elsewhere on this site.

Inspection of the Cat showed no blockage and no damage to the honeycomb inside. It appeared to me not a lean mixture but a very rich one, with black soot deposits.

Im going to test the wires going to the CPS and the O2 sensor and perhaps fuel pressure at the regulator but im just guessing.

Also Ive noticed that if I slowly increase throttle it starts stumbling and backfiring but if I hammer it to WOT it will rev up quick and clean, Its only after 1000 rpms or so while slowly applying throttle does it start to sputter and pop. Hopefully I explained that clear enough to help.

Just a reminder this is an 89 with the Renix system.

I had this problem before and it turned out to be the crank postion sensor just change it an easy fix and not that costly.

Is the #1 TDC sensor inside the distributor working properly? This is the device that tells teh computer that your #1 cylinder is at TDC vs. the #6 cylinder (since they get the same signal when the signal passes through the CPS. I got a jeep once that had that piece broken, and it felt like the engine was in really bad shape. It's the plug that comes out of the dizzy.

Crash- Whats that sensor called and how can I check it? Thanks :read:

Its called the cam position sensor. I dont have my FSM on me so I cant tell ya how to test it. Who did you buy the stroker from? Did they install the timing gears/chain correctly?

AARON

Update- I have replaced the crank position sensor on the bell, cleaned and checked all my grounds and no change. It still starts and idles rough and when any throttle is applied it is sputtering and popping hard. If i hammer the throttle, it revs quick and clean. I very much want to get this figured out so please any help is greatly appreciated. Just a reminder this is an 89 Renix XJ, automatic with a 4.7L stroker and Ford 5.0 injectoers and bored TB. Everything else is as it was on the old 4.0L

maybe give the stock injectors a try.. were your ford's new or used? Either way.. maybe try the stockers..

om3gadagg3r said:

Update- I have replaced the crank position sensor on the bell, cleaned and checked all my grounds and no change. It still starts and idles rough and when any throttle is applied it is sputtering and popping hard. If i hammer the throttle, it revs quick and clean. I very much want to get this figured out so please any help is greatly appreciated. Just a reminder this is an 89 Renix XJ, automatic with a 4.7L stroker and Ford 5.0 injectoers and bored TB. Everything else is as it was on the old 4.0L

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Are those 24 lb injectors? The 19 lb might not be enough for your stroker.

The injectors are 27lb blue tops from ebay and either new or reburb.

Rich mix means unburned fuel from either too much fuel or no spark in one cylinder.
Your red hot CAT confirms this. (I had a floor catch fire in an old Firebird from a spark plug wire coming loose on a long trip.)
your symptoms sound exactly like mine did.
In my case it turned out I had 2 plug wires crossed (I know...bone head move...it was dark and cold and rainy...I was tired...)
Recheck that, you never know.
Also, swapping in the old injectors is a good idea too...but only to see if the situation improves, this is not a permanent fix. The 19 lb injector will not be enough at high RPM while under load for your new engine. While you have the old injectors installed, keep your RPM under 3500 and under half throttle. otherwise you could starve the engine and hurt something.
However you know your 19 lb injectors worked, and they swap in easily enough.
check your wire routing, then initial timing, then start on those injectors. Do one at a time and check to see if the problem goes away.
BTW WHEN you get this to work right, you will love it.