Crazy low rpm knock

[TERBOLASER]

okay i got my logger in and efi pms is in the car now im running a 3 inch cat back 14 b turbo piped with 2.5 inch upper IC and 2 inch lower going thru a FMIC mashimotoand all was running fine untill today . Im getting crazy low rpm part throttle knock like form 2000 up on the logger. it goes from zero knock and spike for 43 ( which when i see naturally i let off. ) what I realized is weird is that if I i go wide open throttle i dont have any detonation count period. but the point is it is detonating and its bad when i finally got home after doing the whole let off the tthrottle coast the car home thing i popped my hood and the manifold was glowing red. Here is another thing on the logger i noticed coolant temperature is way down like under normal temp. and then o on top of that o2 reading is maxed and air fuel guage is maxed. now its not like i haven tried to lean it out but i get scared leaning it out past ten percent for the same exact reason fear of detonation. im gunna check my base timing tomorrow after noon and before then pull spark plugs and see whats up. it just seems so random and also check for error codes. okays guys point me in the right direction please.

[TERBOLASER]

okay heres an update i know its like 5 am andI got exams tomorrow so the fight against knock will have to be swift and fast so i went at it asap. like ten minutes after my first post went out to the garage. popped the hood and went to work I set the base timing to 5 degrees and checked it with an inductive timing light. i dont know where it was before i set it but it was floating closer to ten than i felt it should so i retarded it some till i felt safe.started pulling plugs to see there condition and gap. all carbon deposits on them and all were out of spec like ranging from .030-.035. So i gapped those correctly i took a minute to look at the pistons thru the spark plug wholes i think i got sum heavy carbon build up. which ill clean out with some MCCC engine treatment later on today. relubed the piston in my bov rfl. then checked timing on idle on the logger came up with a stable 12 degrees on idle. checked my error codes none listed on tmo. then moved on to testing .....


this is what happened initial drive out the parking lot was the same but once i got going on the street I watch my logger and i didnt have nearly as much random knock as before. now when the knock is sensed it retards timing until knock is gone. low rpm hesitation is still there till 14b spools still reads pig rich on air fuel and logger o2 readings. now im getting back fire at 4500 rpms. and the manifold glows less. when i checked the plugs for signs of extreme detonation there was none. worked like a charm on my way here so as for the hesitation then burst of power in my power band I have my 4 point tuning (for the moment untill i install the efi pms software on my laptop which allows for 12 point tuning of fuel and timing and boost) i have it set up since its running so pig rich at 2200 rpms to 3999 rpms i have -16 percent fuel then from 4000-4999 range i have -14 and at at 7800 beyond just for kicks i put in -12 percent for both part and WOT settings. I havent messed with the timing yet.

what yall think so far?


futur planns take off exhuast run open down pipe and then in the mean time gutt the catalytic converter. and check for exhuast leaks.

any mor einfo or any for that matte would be great.
thanks--- jacques

[TERBOLASER]

okay well the fuel map from the last post didnt help at all but whats ridiculous is that i richen uit up a bit and it helped out alot alot lesds knock but air fuel was reading hella rich to begin with aany ideas? im stumped and trying to fix this inbetween exams. this is killing me cause of the potential to loose my motor to this. sorta upset that 20 something people viewed this and had no comment on it at all.... but im activley trying to get this fixed. asap

[joeym4130]

Low RPM knock is usually not really knock. Especially if its not happening at WOT. Are you prone to lifter tick ? And did you check your knock sensor? If you're getting a rediculous amount like 43 it is most likely PK. Rich because it's adding uneeded fuel, sluggish because it's taking away so much timing.

[TERBOLASER]

yeah im prone to lifter ticking but it hasnt happened since i put themarvel mystery oil; additiv e in my car until now when only when i poped th hood ofter all that knocking.. uhh im pretty sure the knock sensor works cause its no like its randomly all ove r the place it reads normal 5 kncok like it supposed to then its like jumps for 43 . and if its adding unneeed fuel how doe sthat explain me adding fuel y 4 percent and gaining power and reducing knock.

thanks for the reply

[joeym4130]

uhh im pretty sure the knock sensor works cause its no like its randomly all ove r the place it reads normal 5 kncok like it supposed to then its like jumps for 43 .

What do u mean? You normally read 5 knock??

I didnt read the part about you adding fuel whoops

You said your air/fuel is rich, i take it you have a wideband?

[TERBOLASER]

no wide band I wish i did and thinking on getting one soonfor this problem. but i was going off the o2 sensor voltage and airfuel guage. which both max out rich i mean if your o2 sensor voltage is 1v the highest possible then no mistake im really rich weather a narrow band sensor is accurrate or not its still approximate. i mean normally read 5 knock
is every dsm i have owned and hooked a logge r too they will hav e rand 2- 5 knock count show up on the logger from time to time as long as it does curve up to43 and stays down really low its good. why did you ask about lifter ticking ? really thanks for helping me out man

[joeym4130]

Does your o2 sensor stay at 1v the whole time? Any other info on the o2 readings?

I mentioned the lifter tick, because the knock sensor will pick that up as knock.


I have that problem in the winter, when its cold my lifters tick, and then at part throttle i will get rediculous knock amounts like 40 something, until it warms up and stops ticking. Timing gets pulled, and my part throttle response is horrible, and laggy. First thing I thought of when you mentioned a high knock count like that, and the slow response.

[TERBOLASER]

well o2s arent always at 1v but it goes there at low rpm like i said is gone now because i richen it up 4 percent and it doesnt knock but it still has hesitation and now back fire . and the manifold glows cherry red way more than before.firend had the manifold problem he thinks my timing is off... sigh checking my timing tommorrow
no other ideas lol i got an exhuast leak i found but it would be a mirracle if that was it .

so what else do you think I cant hear my lifters but you say that lifter ticking can set off the knock sensor cause it to pul timing at the wron moment and then every thing goes to shit cause it runns realll rich.

[joeym4130]

If your o2 sensor is not cycling at idle and partial throttle it is dead....

That would cause horrible part-throttle hesitation.

I had this problem too when mine died, but at idle it stayed at 1.00v, which is how i know it died. It sputtered and wouldn't go anywhere at part throttle while driving it. I throw in a new sensor, and it ran like it should.

Check out your o2 sensor, it shouldn't peg and sit at 1.00 at all.

[TERBOLASER]

it doesnt do that at all.it works just like every other one ive ever had o2 isa still good it goes upo and down on idel it just pegs lean under any condition part and wide un less cruising which it goes up and down

[Newlogics]

Does the car leave a black smoke when going WOT?

If you're running pig rich, start leaning it out and look for changes. The knock at part throttle is one of two things:
Other mechanical noise trips knock sensor (phantom knock)
Carbon deposits on valves and pistons are so bad, that valves are touching down (happens more often then people think)
Being a tooth or two off on the timing belt will 'cause that kind of knock as well.

Lean it out at part throttle. At this point fuel doesn't affect your knock (exhept may be you're dumping so much, that you extinguish the spark). You won't damage your engine by leaning it out at low RPM/part throttle if you use commong sense and keep track of things. P.S. Your manifold was glowing red because your timing was being pulled to crap due to know, and you had nice BBQ right inside your manifold.

[TERBOLASER]

well thanks newlogic although i knew most of that already its re assuring to get the similar responses from different people. Now heres what i found out int he last 2 hours ...
took the timing cover off to check my timing and i realized that my balance shaft belt was ####ed and snapped ( now im putting a new one on ) and then the next matter was the oil pull was not in phase problem number 2. timing appears to be on the mark but i took the belt off any ways cause its in the way of installing a balance shaft belt. now after I do those 2 things are fixed ithink it should be fine because before i riched every thing up +4 percent to get rid of knock i had been running the same settings for like weeks and nothing was wrong at all. then 3 days ago all the sudden it started knocking like crazy . so I think the balance shaft belt went out. making the motor vibrate low rpms and the knock sensor would pick this up and retard the timing all the way down and increase fule and it would run horrible and then ontop of that manifold would glow. as a result. and opinions does this seem like it is the case.

[TERBOLASER]

and what do you mean by touching down like taping the pistons?

[Newlogics]

Originally Posted by TERBOLASER

and what do you mean by touching down like taping the pistons?

Precisely.
I have two head sitting here at the shop that have about 1/16" or more of carbon on the valve inself, and at least as much on the piston...

[KAZAM]

sometimes it is the small things we over look i had a simular problem which was caused by a leak around the injector gaskects so check them make sure the injector has a nice snug fit and is seated properly

[TERBOLASER]

will do
im gunna go and replace injectors replace those seals and change the fpr stock one changethe cas . cause its runnign pig rich.

I got a question what does the stock boost guage read off of cause last i heard it was off of fule pressure which is why its horribly in accurate . then i noticed that my friends car that is running fine his stock boost guage doesnt read as high as mine his he asid stops movingat like what he thinks is 8-9 lbs of boost in between the 7 and 14. but mine goes allthe way to 14 like burys its self so im thinking i might have high fuel pressure on another not whats my injector pulse with supposed tobe like on cruise cause under the conditions of horrible acceleration and hesitation it sorta has unusally high pulse widths like 6.82 ive never seen it go past 4 on my other cars ihad in the past on stock injectors etc. so what about that. whats it like when a fpr goes bad the stock ones that is.

[Newlogics]

Originally Posted by TERBOLASER

will do
im gunna go and replace injectors replace those seals and change the fpr stock one changethe cas . cause its runnign pig rich.

I got a question what does the stock boost guage read off of cause last i heard it was off of fule pressure which is why its horribly in accurate . then i noticed that my friends car that is running fine his stock boost guage doesnt read as high as mine his he asid stops movingat like what he thinks is 8-9 lbs of boost in between the 7 and 14. but mine goes allthe way to 14 like burys its self so im thinking i might have high fuel pressure on another not whats my injector pulse with supposed tobe like on cruise cause under the conditions of horrible acceleration and hesitation it sorta has unusally high pulse widths like 6.82 ive never seen it go past 4 on my other cars ihad in the past on stock injectors etc. so what about that. whats it like when a fpr goes bad the stock ones that is.

First off, there is no stock fuel pressure gauge. Stock ECU is pretty oblivious to fuel pressure. Get a gauge (they are cheap) and check your pressure. May be you FPR is screwed or return line blocked.

Secondly, stock boost reading is a calculation based mostly on MAS readings, but also takes intake volume into consideration, so aftermarket IC piping for example, will off-set stock boost guage, as well as many other things.

[TERBOLASER]

hey so you mean to tell me that if i upgraded my IC piping to 2.5 inch uper ic piping and then a 2 inch lower flowing thru a 3inch thick 14 icnh tall 24 inches plus end tanks with 3 inch inlets fmic would that make the stock boost guage go to 14 flat lining.? and how do i check o see if my fuel return is blocked because i just changed my cas fuel rail checked my injectors changed the fpr and every thing so i dont know if my fuel return is clogged
? ohh what if my manifold is cracked and leaking.

[Newlogics]

Originally Posted by TERBOLASER

hey so you mean to tell me that if i upgraded my IC piping to 2.5 inch uper ic piping and then a 2 inch lower flowing thru a 3inch thick 14 icnh tall 24 inches plus end tanks with 3 inch inlets fmic would that make the stock boost guage go to 14 flat lining.? and how do i check o see if my fuel return is blocked because i just changed my cas fuel rail checked my injectors changed the fpr and every thing so i dont know if my fuel return is clogged
? ohh what if my manifold is cracked and leaking.

The off-set I'm talking about is about 2-3psi.

Blocked return line is a far cry. Before you do anything else, get a fuel press. guage and get that possibility out of the way.