AznBlueBoy

ok someone i know has an idle problem and he says the only way to fix it is putting in the injectors from the 4th gen vtec ludes which is the peak and hold..he has a 5th gen with the saturated injectors and did the obd2-obd1 conversion
he thinks that also another way to fix the idle problem is get hondata and tune it....what the hell is that? a car should be running fine without tuning...unless the car is highly modified but his is stock with like intake and exhaust.....and obd1 conversion

WickedSol

tell him to listen to his own advice and get the ob1 injectors and a injector resistor box to go with it and call it a day...

i have a set of rc 370cc injectors that are peak n hold for sale...view the link below:

https://honda-tech.com/zerothread?id=1308283

Lude S

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by AznBlueBoy &raquo;</TD></TR><TR><TD CLASS="quote">ok someone i know has an idle problem and he says the only way to fix it is putting in the injectors from the 4th gen vtec ludes which is the peak and hold..he has a 5th gen with the saturated injectors and did the obd2-obd1 conversion
he thinks that also another way to fix the idle problem is get hondata and tune it....what the hell is that? a car should be running fine without tuning...unless the car is highly modified but his is stock with like intake and exhaust.....and obd1 conversion</TD></TR></TABLE>

I am tuning with Hondata so that it will run on 290cc injectors and I dont like how the car is running too rich.

Lude S

Quoted from Abolute Prelude

I have covered this topic extensively in another forum. Below is the pertinent info from that thread.

In short, no. You can't chip an OBD II to do much of anything. By design, the car detunes itself to factory spec. There are other ECUs you can install with varying success and I cover just about all of them in my post.

This is in reference to doing a P13 ECU(OBD1) swap into a 5G:

I just completed this conversion and I've run into a slew of problems.

First, the car no longer idles correctly. It hunts anywhere from 700 - 1500RPM pretty much all the time. A little bit less while it is cold, a lot more when it is warm.

Second, my MIL is on, but I didn't check the code as I was FORCED to take the ECU out before.................

Third, P13 ECUs running on the 5th generation Prelude injectors = detonation. The injector sizes are wrong (as previously stated by PilotSi). My car is running VERY lean, which didn't occur to me until I read a post on pgmfi describing what Pilot did before. I no longer felt safe driving the car with the wrong sized injectors; risking detonation. If you want a reason to replace your pistons, continue running the stock injectors.

Solution? I took out the OBD I and put my OBD II back in. No more idle problems. Car's mixture is correct now.

I was using a JDM P13, chipped with spoon.bin, RP12 removed for manual operation. Car ran normally aside from the MIL. Pulled very hard in every gear (probably due to it being improperly tuned on the way too damn lean side) and VTEC enagement varied from 5000 to 5300.

To answer the pertinent questions: You will need a LOT more than just an OBD I P13 and a new chip if you're running a 5th generation prelude. You'll most likely need the correct injectors, access to a ROM burner (unless you buy one off ebay), OBDII -&gt; OBDI harness, 10mm socket, and a lot of patience. A WB O2, and A/F meter wouldn't hurt either.

In reference to adding Chips to the ECU

The chips from ebay are basically any chip off the market and its corresponding .bin file. There are no differences between the two. The quality of the chips are irrelevant; its just silicon with 1's and 0's. I have the Spoon .bin file and can place it on any chip I please. Same thing with the stock settings, the KS-ROM, and just about every other ROM ever made for any other Honda.

The change in redline as a selling point, not because of practicality. No one is going to generate power at 8000+RPM without serious engine work. And if you've gone that far you're not using the stock ECU anymore anyway. I've already modified my P13 Spoon program to drop it back to 7700, the stock redline.

The dip gets corrected when you swap to another ECU. The 'teg GSR ECU (P72) corrects this quite well, but you'll get screwed on the bottom end with lower torque. Essentially, from everything I've gathered, the P72 screw you on the bottom end and the P28 (Civic Ex/Si) screws you on the top end. Most people opt for one or the other just because those ECUs are actually modifable. You can adjust the fuel maps to your hearts content as the formulas are known.

Prelude owners are shafted in this respect. I'm working through trying to decode the fuel maps for P13s, but it is slow going. Honda apparently started smoking very good quality crack because it makes no farking sense at all.

In short, If you want it to work and work well, there are two different systems to try.

Hondata is a well respected product that works. It is endlessly tuneable, supported, and has a large community to assist. It is a bit pricey though.

A P72/P28 would also work in a H22. Properly tuned it could give you the "pull" you're looking for. There are lots of ROMs out there for these two as they are the most commonly used (P28 is the 'teg GSR, P72 is the Civic Ex/Si)

v4lu3s

obd1 prleude vtec has injectors rated at 345cc at 43 psi, but it only runs at 38 psi typically.

obd2 prelude has injectors rated at 290cc at 43 pis, but it runs those injecotrs around 50 psi.

take the sqaure root of the new pressure divided by old pressur and multiply it by the original flow rate to see what it really flows.

obd1 prelude: square root of 38/43 times 345 is appr 325cc. turn that down to 36 psi which is within stock spec, and you get 315cc.
obd2 prelude: square root of 50/43 times 290 is appr 315cc. turn that pressure up to 54 psi (btw that is within stofck specified range) and you get 325cc.


so it seems that they both end up flowing the same amount......

WickedSol

yes they are in retrospec...obd1 injectors are peak n hold and the obd2's are saturated...