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the STR has been plaguing me for a wile . its reluctant to perform at top end.
Bad fuel trims .Pinging like crazy at WOT .
even worse when I put the 1.5psi powerhouse pulley on . I done new plugs ,
all the vacuum o-rings and intake gaskets cleaned the MAF , cleaned the T/B . and intake neak. and cleaned out the SC and charge coolers . hell of a mess in every thing , so added a catch can to the PCV . bypassed the EGR . tested the O2's. the fuel trims were better but not great .then we pulled these off yesterday .
yuck those factory cats were severely blocked .
and then fitted these new magna flows.
I'm surprised it could rev past three grand ! 170000km is too long to leave your cats un touched . man it sounds real growly now and with a cackle some what like a f type r ! I'm confident i found my problem . but won't really know till the weather clears up to know for sure . I've reset the KAM and codes (exhaust shop ran the batt flat so there was a smorgasbord of codes ) and i will cruse round a few days till the monitors finish . then I'm sure ill know by then if she's a happy jag. strait away at light throttle though the response is far better or even a bit touchy.
ill be watching my catch cat to see if the oil passing through the pcv has slowed, jugging by the restriction in the old cats I'm shore there should be an improvement there too !
any way for those of you who have not changed your cats yet may be do it before the 100k mile mark as this is a lesson to all of us . there were no codes coming up for these old cats witch surprised me . by looking at them and hearing the difference there really should have been !! hope fully this has sorted my power woes and fuel trims. i will post back when i know .
this is another one of those jobs that left me feeling warm and fuzzy to have out of the way.
I disagree. It depends how the cars been treated and to some extent on luck.
By way of example, people don't always check their fuel trims (ever). So can be damaging the cats. Or they don't change plugs. Same issue. Or they drive through deepish water and cause sudden cooling and damage. Etc.
With the will and enough money then change lots of things that will sooner or later cause faults. The list is rather long, though, from suspension to emissions items, fuelling items and so on.
Thanks Datsports, excellent pictures and straight-forward write-up, as always.
My STR is now at 135000 km, and I am beginning to sense a performance fall-off.
I am sitting on a pair of Magnaflows like yours, waiting for that CEL light, but I think I'll go ahead and fit them. What other changes, if any, did you make to the exhaust system when you fitted the new cats?
Thanks Datsports, excellent pictures and straight-forward write-up, as always.
My STR is now at 135000 km, and I am beginning to sense a performance fall-off.
I am sitting on a pair of Magnaflows like yours, waiting for that CEL light, but I think I'll go ahead and fit them. What other changes, if any, did you make to the exhaust system when you fitted the new cats?
it seems you will be waiting for the car to throw a MIL for a very long time .
mine never did and they were past it !!
my car when i purchased it was not thrilling like i had imagined . in fact i have a datsun 1800cc (180b) with 230hp at the wheels and for acceleration the datsun seemed to have lot more pull than the STR, shore its 1/2ton lighter but it didn't seem right . so i ran the jag through a few dynolichous quarter miles that calculated 278hp at the wheels .
so first thing i done was cut the exhaust off behind the cats ran 2.5'' pipe right through . and removed the center twin through chamber, and fitted an x pipe in its place and replaced the rear silencers with 2.5'' step through chambers .thinking opening it up would help. it sounded great except a bit of a rasp between 2000 and 3000rpm wasn't too loud .
defiantly went better 294hp ATW .STILL NOT GOOD. since then I've done custom intake j pipe and mina cold air kit ,
new spark plugs , and a power house 1.5 pulley . it all helped a little but it did not give the gains that others report . and strangely after all these ''upgrades'' it still wasn't making anywhere near as much power as new stock standard STR. actually 314hp ATW . around 370bhp i knew something wasn't right as its pinged ever since i bought it . the cat back pipe removed a bit of the pinging and so did 98ron fuel. the pulley made it worse again .
any way after a bit of a run today i can guarantee these cats have woken this thing up its an animal !! any ways its now too loud the old strangled cats were my mufflers ! so i booked it in for monday and i will be shifting the x pipe forward as i read that it needs to so many inches rearward of the cats , so i will search again as to how far back soon . and i will re fit the original center twin through chamber/resonator. hopefully that will be that. it feels like a different car . and thankfully in a good way
yes Cambo .it was your thread that made me click, as the pinging was getting on my nerves . and after searching many threads about pinging and reading that it is not possible for this car to ping due to knock sensors so on and so forth, i came across your thread massive read that it is . you were the most help and saved me a set of coils cause thats what i was about to do next.
i could acutely feel the timing getting pulled back a little bit almost like a miss but far to subtle to be missing. but the pinging never really stopped unless i backed out of the gas . it has power there now i never felt before . as i keep saying this car just gets better and better , however that doesn't say much for its condition when i bought it aye . i can't imagine that even treated really well that those tiny cells in those 600 cell cats could possibly make it to 200000km they are **** !
Big clue there - working STRs do not ping. Classic sign of damaged cat(s).
not wrong there . i know this now . never had this before , except with cars fitted with a distributor normally no cats to blame on those , most jap cars I've worked on over the years throw a code to send you to the problematic cat , but most of those cars did not ping at all , but keeping in mind that they were inherently gutless before the cat failed and pulled back the timing to be even more mundane .i guess the owners just got used to it , most small car owners are happy if it just gets them to the shops or work and back , up until the mil comes on . still blows my mind that my STR MIL did not come on , the cats were done . strange ! seems to be common with these jags with a few miles on them , as you pointed out many things can kill a cat, but surely the monitors should have noticed ?
Many bad cats do show up and you get codes or weird fuel trims (there are lots of threads on this site about this).
But... some are mainly bad at WOT. The PCM is staggeringly busy at WOT and OBD allows (requires?) it go open loop. So I think it can be unable to see the problem. (And the O2 sensors can be untrustworthy at very high power / gas flow.) Plus, at WOT it dare not go lean so goes rich to protect the engine. (I'm sure you've seen dynos where AFR is a bit too rich really - because the PCM is set to be cautious.)
With a lot of cars you can stick it up on a lift, rev and listen to the cats. You don't even need to go to WOT to hear the common failure of a broken up cat. Or you can use an IR gun and see the temp drop is wrong. And then there's exhaust gas analysis to show a cat isn't working right.
I certainly agree that at 170K km (or whatever) it's worth doing some testing, especially if you'd like as many HP as the car has a decent chance of producing.
I suppose watching MAF at WOT ought to provide a clue because it will indicate less air flow than there ought to be. (And then you get to scratch your head as to why. Blocked cat is not the only potential cause.)
yes Cambo .it was your thread that made me click, as the pinging was getting on my nerves . and after searching many threads about pinging and reading that it is not possible for this car to ping due to knock sensors so on and so forth, i came across your thread massive read that it is . you were the most help and saved me a set of coils cause thats what i was about to do next.
i could acutely feel the timing getting pulled back a little bit almost like a miss but far to subtle to be missing. but the pinging never really stopped unless i backed out of the gas . it has power there now i never felt before . as i keep saying this car just gets better and better , however that doesn't say much for its condition when i bought it aye . i can't imagine that even treated really well that those tiny cells in those 600 cell cats could possibly make it to 200000km they are **** !
I'll never forget my drive home from Castle Hill Exhaust after having the cats changed, I nailed it on the motorway on-ramp and the engine pulled hard and strong all the way up to rev limiter, so quickly it caught me by surprise (i had the shifter in 2nd, was going to manual shift) it had not pulled that hard or quick in a very long time. No pinging, no hesitation, just BAM! I was so elated I was laughing and giggling, banging my fists on the steering wheel yelling YES YES YES YES!!!! it was such a relief...
Sorted alright! Wow this thing is way quicker than ever . Done a few hundred ks now since , so done a bit of testing
Every thing has passed bar comprehensive, fuel trims are grate .
Night and day is an under statement . The Datsun ain't got a show now !
I done a few timed runs , could only get one good one off the mark without wheel spin .but still lost a bit in to second .
I'd be worried (not as bad as a panic) if any monitor didn't set fairly quickly if you've tried the (drive cycle etc) info in the codes PDF or failing that all manner of varied driving over a week or two.
The PDF is pretty detailed.
EVAP can be pesky but as yours is set no need to worry about it.
The cats seem good for 100K miles (160K km)
I swapped to 100 cspi units at 150K km but this was before pinging effects were present
I think Cambo was just over that number when the pinging started
100 cspi certainly liven up the S/C cars. The exhaust not changed with the cats and OEM exhaust. Ive since gone to a 2.5in system with no center resonator or muffler, just the rear boxes. It defiantly too loud and does not add much except noise. Ill be quietening it down soon so it somewhere in the middle keeping the note and losing noise
I'd be worried (not as bad as a panic) if any monitor didn't set fairly quickly if you've tried the (drive cycle etc) info in the codes PDF or failing that all manner of varied driving over a week or two.
The PDF is pretty detailed.
EVAP can be pesky but as yours is set no need to worry about it.
im not stressing yet it normally takes two to for days to complete comprehensive for me anyway . as i just drive it how i drive it with the addition of the long deceleration from around 100kph to 40kph ,and a consistent 100kph haul for a few mins . evap has had me over a barrel a few times but i was running my fuel too low then too full then obveastly just right ,when it got down to 3/4 it just passed for me so that wasn't an issue this time . hope fully it will pass comprehensive soon and i will be out of the woods . i have no access to jtis as I'm apple only . i do have all the pdf's but nothing is file named just coded . so that just screws with my head looking at them . i will buy a PC one day soon just for it . but cheers for the pointers any how !
The cats seem good for 100K miles (160K km)
I swapped to 100 cspi units at 150K km but this was before pinging effects were present
I think Cambo was just over that number when the pinging started
100 cspi certainly liven up the S/C cars. The exhaust not changed with the cats and OEM exhaust. Ive since gone to a 2.5in system with no center resonator or muffler, just the rear boxes. It defiantly too loud and does not add much except noise. Ill be quietening it down soon so it somewhere in the middle keeping the note and losing noise
I want a bit more of the sleeper factor back
Cheers
34by151
i wanted to go with 100cells but was warned off them buy the magna flow sales rep . saying that its more for race application and there is a much smaller aria of metalised surface . and basically would not last as long as 200cells . I'm happy with these to be honest new 600cell would have also been a huge improvement too. but don't fear it is certainly livened up ! i now know how cambo felt on his drive home ! I'm ecstatic with the performance . what a car
Great news It passed all 8 monitors tonight . And no codes , We're good to go !
I do have the jtis down loaded on OS , and it shows all files but will obveastly only open the jpeg's & PDF's . The hard part is finding what you want as there is no file headings , just codes I've seen a lot of exploded veiws but with no text . And mostly not what I'm looking for . Never thought I'd say it but I need a PC ,
Great news It passed all 8 monitors tonight . And no codes , We're good to go !
I do have the jtis down loaded on OS , and it shows all files but will obveastly only open the jpeg's & PDF's . The hard part is finding what you want as there is no file headings , just codes I've seen a lot of exploded veiws but with no text . And mostly not what I'm looking for . Never thought I'd say it but I need a PC ,
Glad you resolved the issue you had. I've been wanting some high flow cats for a while and at 76k, the stockers aren't going to last a whole lot longer judging by these threads. What part number of Magnaflow did you use and did you use any o2 extenders?
07-13-2016, 12:17 AM
170000km is too long to leave your cats in .
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