First off, the car: 1998 Civic EX coupe with Full JDM GSR swap and t3/t4 setup running at what is supposed to be 8.5 PSI. fully functional obd1 ECU chipped (o2 sensor bypass) and it was pre-tuned for a very similar setup on my old 1994 integra GSR. 1000cc injectors with walbro 255lph fuel pump and fuel pressure regulator. FMIC.

Brief history: i sent the head out to get machined, cleaned and prepped for my FI setup. While it was at the machine shop, they called me and said that one of my lifters was a little bit bent and suggested getting a new one. I had them replace that lifter (OEM). New gaskets all around, ARP head studs, and a block guard as well. New timing belt also. All stock internals. I'm currently in the process of breaking in the car, so I have not beat on it, nor have i really tried to crack Vtec yet (one time for a test as explained below).

The issue: Well, under roughly 4000 RPM, the car runs alright and boosts just fine... but when I floor it, it chokes up a few times until i hit roughly 4000, 4100 RPM then the car just craps out and chokes up, as if it were hitting the rev limiter. (makes a very loud backfiring or misfire noise). My initial thought was that I might have an issue with Vtec timing, considering the ECU has already been pre-tuned on a different car with the same essential setup. So, I ran my own diagnostic test and slowly pushed the car (kept it in vacuum, no boost) past 4100 up to roughly 4600 and Vtec cracked in right where it is supposed to (4400 RPM). When I boost the car, even the slightest bit, is when this happens. I can hear the turbo continue to spool up but the engine just chokes and the car doesn't go anywhere, like I descrubed above.

Lots of things have ran through my head such as a bad tune, distributor timing, fuel pressure (although it's currently set at 50 for idling which is higher than normal), even possible mechanical issues internally (which I'm hoping to god that it's not). I'm thinking of taking it right over to DSG and just have them check it out and re-tune it if need be. What would you HT guys suggest the problem is?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 8YourV8 &raquo;</TD></TR><TR><TD CLASS="quote">First off, the car: 1998 Civic EX coupe with Full JDM GSR swap and t3/t4 setup running at what is supposed to be 8.5 PSI. fully functional obd1 ECU chipped (o2 sensor bypass) and it was pre-tuned for a very similar setup on my old 1994 integra GSR. 1000cc injectors with walbro 255lph fuel pump and fuel pressure regulator. FMIC.

Brief history: i sent the head out to get machined, cleaned and prepped for my FI setup. While it was at the machine shop, they called me and said that one of my lifters was a little bit bent and suggested getting a new one. I had them replace that lifter (OEM). New gaskets all around, ARP head studs, and a block guard as well. New timing belt also. All stock internals. I'm currently in the process of breaking in the car, so I have not beat on it, nor have i really tried to crack Vtec yet (one time for a test as explained below).

The issue: Well, under roughly 4000 RPM, the car runs alright and boosts just fine... but when I floor it, it chokes up a few times until i hit roughly 4000, 4100 RPM then the car just craps out and chokes up, as if it were hitting the rev limiter. (makes a very loud backfiring or misfire noise). My initial thought was that I might have an issue with Vtec timing, considering the ECU has already been pre-tuned on a different car with the same essential setup. So, I ran my own diagnostic test and slowly pushed the car (kept it in vacuum, no boost) past 4100 up to roughly 4600 and Vtec cracked in right where it is supposed to (4400 RPM). When I boost the car, even the slightest bit, is when this happens. I can hear the turbo continue to spool up but the engine just chokes and the car doesn't go anywhere, like I descrubed above.

Lots of things have ran through my head such as a bad tune, distributor timing, fuel pressure (although it's currently set at 50 for idling which is higher than normal), even possible mechanical issues internally (which I'm hoping to god that it's not). I'm thinking of taking it right over to DSG and just have them check it out and re-tune it if need be. What would you HT guys suggest the problem is?</TD></TR></TABLE>

get the car tuned. could be as simple as just blowing out spark if the plugs are gapped too wide. but if you dont have a wideband on the car, and havent gotten it tuned, i wouldnt expect any better.

 

tuning and spark blow out will cause all kinds of fun issues...

 

alrighty well thanks, i figured that was the main issue. gonna check on gap reccomendations and tweak as necessary, and take it to DSG for a re-tune. maybe i'll just have them gap my plugs and tweak my dizzy timing as well, might make more sense.

 

double check tps/ map sensors are plugged in correctly - seen this happen many times
if this checks out fine - most likely need tuning, if it leans out a lot it will hesitate/choke/etc.

Best of luck

 

Tune it for your setup. Every motor is different along with many other things i'm sure. Sounds like to much fuel if it chokes up and backfires. Get it tuned and you'll be fine.

 

yeah tuning will be done on monday. i'm actually more convinced that this has something to do with spark plug gap and possibly my plug wires as well. i did all of the turbo work myself and i had the shop put the head back on, they decided to put the spark plugs in themselves and i am unsure as to weather or not they gapped them properly. i'm currently running NGK copper 7's. i have read up on HT over the last few hours trying to determine what the best gap is for my setup, and i've seen most responses to be roughly .028 for similar boosted applications. can anybody agree with this or leave their gapping experience input, please... thanks

 

.028 will be more than likely fine for your setup.

 

are you running the stock heat range plugs? try running 2 steps colder plugs. NGKs are what you need.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 8YourV8 &raquo;</TD></TR><TR><TD CLASS="quote">yeah tuning will be done on monday. i'm actually more convinced that this has something to do with spark plug gap and possibly my plug wires as well. i did all of the turbo work myself and i had the shop put the head back on, they decided to put the spark plugs in themselves and i am unsure as to weather or not they gapped them properly. i'm currently running NGK copper 7's. i have read up on HT over the last few hours trying to determine what the best gap is for my setup, and i've seen most responses to be roughly .028 for similar boosted applications. can anybody agree with this or leave their gapping experience input, please... thanks</TD></TR></TABLE>

but thanks lol