gsr swap in eg hatch

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dream_chasing

New Member
so I just picked up a 95 civic hatchback with the b18c1 in it with a p28 ecu.. the car runs really rough when first started.. barely idles if it idles at all without slightly reving it. would tuning tuning the ecu help? I changed the spark plugs & I have no difference.. the guy said it was semi built with crower cams, itr pistons, walboro 255 fuel pump, etc..
 
tune wouldn't be the first place i would check. if it was "built", the head was off at some point. I would check the timing and then do leakdown and compression tests.
 
after it warms up , it idles at 1k rpm perfectly.. not sure if that helps any but I'll look into the timing. I appreciate the reply!
 
does it ever stutter or bog down when you are driving it or is it just a low idle at start up and then it's fine?
 
it doesn't bog unless I'm around 2k & I give it some gas but it doesn't necessarily bog.. just slowly pick up rpms until 4k.. it has plenty of power on top end.. the guy I bought it from told me it needed to be tuned but I'd like to hear you guys input on it. I was told it was built but I have no proof on any of it.
 
it doesn't bog unless I'm around 2k & I give it some gas but it doesn't necessarily bog.. just slowly pick up rpms until 4k.. it has plenty of power on top end.. the guy I bought it from told me it needed to be tuned but I'd like to hear you guys input on it. I was told it was built but I have no proof on any of it.
yeah, that's the hard part about buying someone else's project car. you should have pretty linear power. it shouldn't be slow to pick up. if it "pops" at 4k, sounds like they may have adjusted the vtec. here is a relatively stock gsr power curve.

2mxhpiv.jpg
 
Do you know if that p28 was chipped? if it's a stock program, that's probably an issue. if it does have a 'p72' map on it, or was custom tuned at some point, it's probably the tune.

idling at 1k is probably too high (800 is fine)
 
especially when it's my daily LOL I don't recall it popping at 4k.. I know the vtec crossover is very loud though.

the guy told me it was chipped & that it'd run better after it was tuned but that's all I really know. not sure what all has been done to it. if it was a timing issue.. wouldn't it run rough whether it was cold or warm? just wondering.
 
so I fired it up & idled it til it got warm & disconnected the tps sensor.. is that supposed to affect the idle? cause it didn't change it at all.. it kept idling around 1k.. but the other day , I disconnected the map sensor & it shut off instantly. (sorry , don't know much about hondas)
 
taking sensors away will not make anything run smoother.

Is it throwing a check engine light?

if its chipped, it's probably just a basemap.

I'd highly suggest investing the couple hundred bucks to strap it to a dyno with a honda tuner, someone who can burn you a chip
 
yeah , I'm going to get it scanned tomorrow & tuned at a shop near my house.. it was someone else's project so I honestly don't know what all could be missing. i wouldn't mind spending the money if only I knew it'd fix the problem.
 
I say the guy is crazy thinking a tune will help it run better. Unless it's a big time build with crazy cams, it should idle like a dream....chipped or not.

My focus would be troubleshooting: (Helm's Manual for the win)

Fast Idle Thermo Valve

Idle Air Control Valve

Throttle Postion Sensor

Mass Air Pressure Sensor

Distributor

Also....taking the cover off the ECU will show you if there is a chip or not.
 
so.. I took it to the shop today & the guy said that the P28 isn't even chipped.. he has no idea how it even runs.
 
Who ever sold the car to you is a real piece of work. Either he's shady or very uneducated.
 
he must be quite shady , I wouldn't exactly say the wiring in the car is decent.
but the guy at the shop is on the look for a ecu.. he'll chip & tune it himself for around $150
 
but why exactly do people go after the p28 for a gsr swap? does it perform better than the p72?
 
It's more abundant and easily used for Bswaps (with a chip). There's not really any difference between P28 and P72 once they've been chipped. Heck, guys can chip a OBD1 P06 ECU (D series non VTEC) and make it work for your set up too.
 
ahh okay , so if I were to get a hondata s300 p28 ecu.. would it perform better than a crome p28? cause from what I've read, the stock p28 is used for a sohc motor which is causing it to run lean.. right? what's that mean for the cam shafts?
 
p72 offers IAB control (intake manifold secondary butterflies on intake gsr IM) and knock sensor hook ups over the p28. the sohc vs dohc doesn't matter- it's all on a belt and the ecu doesn't do anything with it.

These are just circuit boards and the base of the boards are similar if not identical. And with some soldering and some EEPROM chips installed on the generic core, it can change functionality.

if you're not running a gsr head/with the gsr IM, there's no need for the IAB, and most tunes ignore the knock sensor and run their default map at wide open throttle.

crome is a cheaper alternative to hondata. both change the stock fueling data tables to custom values to match what the tuner makes. crome is a bit 'do it yourself' where as hondata is the more professional solution.
 
ahh okay.. I think it's a type r im or something like that.. I'm considering a hondata ecu just so it'll be something good.. and will have it tuned professionally. but I guess a stock p28 will explain the idling problems.
 
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