OK, well it started getting worse, surging happened whenever I accelerated. Installed new MAP sensor and works much better, but still slight surging when on highway passing, or on uphill. I was going to swap out TPS, but screws have star type heads. I tried to remove, but i think i just stripped them out. Is there a special tool for this? Or are they just really tight?

 

Those bolts are Torx bolts. If you are going to purchase torx bits. I recommend the tamperproof set so you can remove both standard Torx and tamperproof torx bolts.

 

Well, got it taken care of. First swapped Map sensor and seemed to help a little for several days. then swapped TPS. Issue still came back. Then on a whim, swapped Spark plugs. They were very worn and caked with ash. after swapping plugs, feels like new engine. Next time I will check for cheap and easy fix instaed of almost loosinf finger trying to remove security torx head screws without proper tools.

 

Not to insult you, Pyro, but what does you air filter, fuel filter, cap, rotor, wires and oil and oilfilter look like? Ever pumped the grease zerks and checked the fluidlevels in the diffs, TC and tranny? Considering this is the first time you looked at your plugs, there are more maintenance issues that might get you into trouble...

 

No worries, thats why i post here to help find what i am not looking at. All of the items you brought up are deffinatly valid, but had been taken care of in general upkeep. Using K&N air filter cleaned every 3-4 months and well oiled. Replaced cap rotor and plugs approx 8-9 months ago. (this is why i did not immidialty check them)I did forget to mention that replaced fuel filter and was definaltey time to change, lots of junk in filter. i may need to switch were i get my gas. Diff, and tranfser case were just service less than 6 months ago, and transmition fluid is full and still feels strong. Thanks for the ideas. when i took plugs to mech freind, he said he has seen more and more plugs like this, possibly due to lower grade fuels that are costing us more. Not sure how true this is, but it gives me anouther reasons to complain about the gas prices.

Thanks again!

 

OK, that's interesting. I never managed to really wear out my plugs. I replace them every 2 years, but they look like they have been in there for only a month or so...

 

Interested in knowing what make, and how long you ran those plugs. I just changed mine after a year just to see what kind of wear they were getting. The gap wasnt off, and there was the usual brownish ash on them. 27,000 miles and looked like they could have handled more. BTW they were 'run-of-the-mill' Champions.

 

Most wear on plugs comes from rich/lean running conditions. They do wear out but for the most part if you pull them every 6months, clean and re-gap you should get atleast 50k out of el cheapo plugs(this is if the car/truck is running right, bla, bla,bla. We all know this. /ubbthreads/images/graemlins/smirk.gif)

No as to the surging and what not. I have no Idea. I'm having a back fire problem on my 89 4.0l6 that I cant trase down. I replaced and checked just about everything that will cause back fireing(B/F) through the TB: new fuel pump(most B/F I have come to find out with hours of searching is fuel delivery related) fuel filter, plugs cap rotor, adj TPS, replaced coil/mod, repaced MAP, checked EGR it seams right. I have not replaced 02 yet or pulled injectors to test. This has me /ubbthreads/images/graemlins/wall.gif It happens about 1/4 throttle to WOT, at WOT it runns great but at WOT a lot of the sensors are bypassed(so I have been reading)I have never come across this problem with the renix XJs in the 8yrs I have been selling/working on and driving them. Time to see what you all think...

Wow talk about long winded. thanks everyone...andy /ubbthreads/images/graemlins/bow.gif

 

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Most wear on plugs comes from rich/lean running conditions

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And:

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I have not replaced 02 yet or pulled injectors to test

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There you go. Especially the O2 sensor gets slow when it gets old, causing rich/lean conditions as it's slow reading the mixture condition, so the ECM isn't correting injection fast enough. An injector that's a bit leaky at the nozzle causes a rich/lean condition. Especially if it's only one, thus leaning out the mixture in the cilinders with the healthy ones.

Check if your plugs all have the same color. If not I'd say injectors. (Run some cleaner first before tearing everything apart) If they are the same I guess it might be the O2 sensor.

 

I'm starting to think/feel it's the O2 for it only happens after about 5-8mins of running. I'm hoping to get a lil down time and an open bay in the shop to work on it. Will post up what happens after O2 is swaped out...andy

 

I was running regular Champions and replaced with copper core champions. The electrode was worn, but not gone. and one had part of the porcelin missing. They all seemed to just have a lot of ash built up onthem, no oil or brown dust. I think part of the issue was that wife was driving back and forth daily to San Antonio at least six days aweek for work and family for almost a year. so from Austin trip was atleast 120 miles a day usually 150-160 a day. so that is a lot of miles and what made it worse was construction on highway made trip mostly stop and go instead of normal highway driving. I'll just keep an eye on it for now an see if it changes from daily driving here in Austin.

 

Well...I replaced the O2 today along with a diffrent fuel reg. No change. I did a 4th fuel pressure test and found I'm only at about 20-30psi w/ the vac line on the fuel reg(should be 32-34psi with vac line off the fuel reg. psi drops with line off from 36-38psi) Soooo I'm pulling the Autozone pump out tomarrow(long story on why I had to get an Autozone pump) and replace it with one of my lots front row GOOD running XJs pump. If this stops the B/F then I'm getting my 130$ back and I have new junk on my 4.0l6 that it needed anyways. Now if this does not fix the B/F then it's tear down of the motor, pull the timming cover off check chain, if it's good pull lifters out and inspect, if wore replace lifters and maybe cam. I rebuilt the motor 4yrs ago around 45-60k on rebuilt motor, cam was good at tine...One more day of not driving the heep. I need to get this fixed, it's eatting up my tine to fix the rest of my junk: 68 Valent needs tranny, 86 MJ needs tranny/x-case put back in, 67 Bel Air needs motor rebuilt and put back in, 68 A/H Sprite needs motor/tranny/rear end needs put back together, bla, bla, bla /ubbthreads/images/graemlins/violin.gif...HAte beeing a gear head somedays...Time for a tall Captain /ubbthreads/images/graemlins/40BEER.gif...andy