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Discussion Starter · #21 ·
Ok, well definitely a late response here but, I am not able to hold consistent rpms, what's happening is that, on my tachometer it's showing when I'm at 2k rpm that's its a steady held rpm but every single time I check the recorded data it's showing fluctuating rpm and I am not seeing it I live data, like I said when it's running it'll show solid held rpm but not in the recorded data so if there's any other way to figure this out without the rpms/ fuel trims and etc I'm definitely open to ideas, just as a side note: I check fuel pressure on 1 prime and it primes up to 40 psi but the Chilton manual says it should be between 25 - 33 psi, I replaced the fpr and exact same reading, I also correctly calibrated the tps exactly step by step from the same manual, take note my throttle body is equipped with an isc motor so as per the procedure I placed a 0.14" Guage between step screw and the dmm reading was at 1.00v which is within spec, spec states it should be between 0.90v-1.02v however I've noticed as I open the butterfly to wot, it's showing me that the volts stop at about 3.9v but spec says it should stop at 4.85v-4.95v and I have an original tps and a new one I bought and they both read the exact same result no change, are these differences something I should further into or is that fine to be off by 1v? Also another note to consider, before I cleaned the map sensor using maf cleaner, the map data was showing inconsistent results, as in there would be brief moments the data showed nothing as if the sensor was not sending any feedback at all then would pick up again but after cleaning it, the results became constant so idk I'm starting to bet its probably the map giving off corrupted data or just refrence data based off the other sensors but I've also noticed my downstream o2 is flatline fuel trim is that normal? I've basically been told through other mechanics in my learning process to pretty much disregard the downstream o2 because it's the upstream that makes the most difference but also because the cat will have changed reading to the downstream o2 compared to the upstream that sensors the raw combustion in order to determine stoichiometric afr or as close to as possible and as a result I disregard all data from the downstream o2 completely, but as part as my diagnostics so far, I've gone through all of fastec, it's got fuel, it's got air, it's got spark mind you my plugs are heavily fuel fouled currently but only been used about 4k kms still full electrodes so don't really want to replace them when they got at least 16k kms left of use, the timing is set to 0⁰ tdc cylinder 4 compression stroke as per the alignment marks and alignment procedure, not sure if I should be independently adjusting the crank to 5⁰ btdc off the belt so as to keep cam position at the mark, just an idea I had but based on what I know the 5⁰ btdc is what the ecu runs the engine at not the actual set sync between crank/cam, exhaust is free of any restrictions, my mpfi system does not use an egr system (literally no mounting points on exhaust/intake manifold, block or throttle body trust me I've checked this thing inside out for the last 6 yrs for it and it does not exist within my system, compression WAS shit at one point showing something like c1- 100 psi c2-120 psi c3-120 psi and c4-10 psi, yes I know that c4 being 10 psi isn't even enough for combustion I know for combustion to occur compression needs to be at least 50 psi. So, I rebuild the entire engine myself, honed the bores, and put in a new set of rings to each cylinder checking all tolerance specs along the way, I clocked the rings exactly as the book states, checked ring end gap, I even recorded all previous dimensions and new dimensions, nothing really changed except being that now all ring clearance is within spec, I actually wrote a 10 page builder spec sheet for all these dimensions between rod clearances block/head surface is at .001" and is within the minimal. 002" clearance spec I machined the furnaces and soooooo much more, long story short, it's got all new gaskets including a multi layer head gasket, and compression reads 150-170 roughly psi nothing exceeding the 15% difference between any cylinder accros all 4 cylinders so it's got strong compression. Final notes: the engine eventually wouldn't start before I rebuilt it and now she fires every time except after running it and when I pull plus to inspect running conditions I can both see and smell they are heavily fuel fouled but my question is what is causing my ecu to run my engine in a rich condition ? Last time I dealt with a rich condition was on a 99 jeep grand cherokee and all I did was replace the upstream o2 sensor then bam! Ran like new rich condition solved but here's the kicker, I tried that on my swift g13bb and slight improvement but still hard hesitation under load, if I'm on a flat surface I can get the speed to climb extremely slowly but as soon as I hit a slight incline/bump it stops climbs speed and slows and basically tries to stall unless I let off the throttle then it limps no problem it's only when I tap the throttle when it bogs and tries to stall and I've noticed the problem is sooo much worse under even like 5% load so in terms of fastec, every crossed off the list it's got it all so at this point I'm thinking it's gota be a crucial sensor misreading some crucial data? My best guess based on all my diag info here is replace the map and go from there? I've also been told try coolant temp sensor, sometimes if that acts up it can cause a headache of problems just like mine? Both my map and coolant temp sensor are both original from factory but coolant temp shows correct data on the cluster and my data scanner so map?
 

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Discussion Starter · #22 ·
I'm clearly a newer mechanic I've only worked on engines for the last 5-6 yrs but I've mostly done maintenance/replacement work and SOME diag work nothing major until this, is there something I'm missing here that an older more experienced mechanic might see I'm missing to check? I've pretty much tried everything I've learned so far but I'm determined to figure this out, should I test anything else for any other important results required? I'm honestly about to start blindly replacing all the sensors until one eventually works lol I'm just trying to learn a more proper way of diag this so if I ever come across it again in the future I'll have the knowledge to go straight to it instead of wasting so much time and money but then again, that seems to be how most mechanics I know work, they pretty much just tell you to figure it out yourself ffs I'm trying but seem to be stuck on this one
 

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Discussion Starter · #23 ·
Here's my best shot at the rpm at 2k and 3k control and disregard the data cut my scanner doesn't record data when I'm viewing in live data and when it cut out was when I was viewing it in live data to better pinpoint the rpm or try anyway but my foot is not doing the fluctuation that's just what it records the data as I can include any other data requested as well
 

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Discussion Starter · #24 ·
Just figured I'd report back here for the conclusion/final fix, after doing some fiddling with throttle cable and got everything back to the stock position, I went ahead and adjusted my timing via crank angle, in case anyone is having this "bog/power loss issue" it's was my timing that was off. I did more looking into my data and discovered my timing being off as in, it was too far retarded and essentially was firing too late which is where i was losing my power, after doing a fck ton of research about initial, base and total timing I realized where I could adjust my timing since it's efi the computer does majority of the "on the fly timing tuning" and so what I did was, I disconnected negative terminal as per every procedure evolving electrical, removed air filter/piping, alt belt & p/s belt, water pump pulley, timing cover then put the crank bolt back in the crank pulley thread without crank pulley and moved the crankshaft to tdc of cylinder.4 compression stroke, removed the crank bolt and loosened timing tensioner and removed timing belt, moved the crank back 5⁰ btdc and made absolute sure the cam lining mark stayed exactly on the mark and put the belt back on, turned twice to smooth out slack tightened tensioner and put everything else back on in the reverse order of removal. Essentially I advance my crank angle timing to 5⁰ btdc and as soon as I fired up she ran like gold again and I now have my car back to life so far everything's going very well very responsive and definitely like I remembered it driving just quicker! But thanks for all the help though was totally appreciated!
 

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Not sure you know what you are doing, the crank/cam angle has nothing to do with the ignition timing...

The CAM must be in sync with the Crank (engine timing), once that is correct the ignition timing can be set at 5 BTDC.
 

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Discussion Starter · #26 ·
Yes the ckp/cmp have everything to do with the ignition timing, without the position of crank/cam pickup angle the ecu wouldn't know where the crank or cam is ... LOL! But I've got a missing tooth reluctor wheel on my ckp that my ecu gets the ignition sequence from both the positions of ckp/cmp in order to determine ignition timing, the sequence itself is programmed and not changeable unless I use a standalone and tune the sequence myself, either way when I built this engine I forgot to short the base tune wire to put the ecu in base tune mode, so I left the crank angle at 0⁰ dtc of cylinder 4 comp stroke and my ecu tuned its own timing to that, basically to simplify in layman's terms here, my ecu thought the 0⁰ dtc i set was 5⁰ btdc and was firing about 5-10⁰ atdc which was way too late to fire this engine, optimally runs at 5⁰ btdc so, I had 2 options either i could keep the 0⁰ tdc and put the ecu in base tune mode to correct the timing issue, but instead I left the tune as is and moved my crank angle back to 5⁰ btdc and guess what? It worked! I got this method from a few old guys I knew who showed me how to tune timing for carbs turns out it works with efi engine too! Big ol secret I discovered and I'm simply just passing this info onto the less experienced mechanics than myself who typically don't get told these kind of secrets cause of middle aged stubborn pos mechanics who think keeping all these lil tricks/ secrets to themselves will make em more money cause nobody else knows them, well idgaf about the money I care about good running engines and if it means taking away potential sales from these kind of guys well in a heart beat ill be saving others money and just giving them the info for free. Too many gate keepers in this trade and I definitely intend to change that oh and btw I've got an 87% passed ASE certificate no prior training or studying that was just on what I knew at the time I took it and IF I didn't know what I was doing then when I built my g13bb from LITERALLY block up it wouldn't have ran at all not to mention its already ran over 1,000 km's and no troubles, other than the temporary timing issue that I've minipulated/corrected, I've checked comp in all 4 cylinders and it's nice and strong along with proper cooling/regulation and good oil pressure and after everything I've done I decreased my 1/4m time by 2-3 seconds as per my new average but uh yea sure what do i know tho eh? 🤣
 

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So what you're saying is you're not running the OEM engine management system, and the ignition timing is derived from a missing tooth reluctor wheel on the crankshaft pulley - if that's right all you needed to do was move the reluctor pickup by 5*.
 
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