Hello All,

I did a gsr swap on my car. It's a 1994 gsr in a 1992 civic. I had to run the vtect wiring and the redo the harness for the dizzy and the injectors because when I purchased the swap the previous owner was running OBD2 injectors and Dizzy. All I did was cut my original engine harness at the distributor to repin it to made with the OBD2 distributor side clip. So now my dizzy has OBD2 clips on both sides within an OBD1 harness.

Same deal with the injectors. I clips them and redid them with obd2 clips. Now, the car starts up fine and ignition timing is fine as well. However, I cannot rev past 3k rpm at idle or under engine load. The only CEL light I am throwing is a 14 (IAV). I am not throwing any dizzy codes or injector codes. Anyone know what the problem could be?

I have searched around but most post indicate the crank sensor or dizzy and those turn out to be OK on my side when I test with my multimeter. I also tried resetting my ECU by pulling the ECU fuse out for about 5 minutes and still nothing. I don't have any vaccum leaks either. I tested by placing a propane bottle to all hoses.

 

So to confirm, the car idles fine at about 850 but won't rev past 3K. I swapped the ECU from my chipped p28 to my original LS p75 ecu. When i put the p75 ecu in and started the car, the idle is at 1,500rpm. I also hear A LOT of vacum from the throttle body top hole. If I put my finder in it, the idle relaxes. This does not happen with the p28 ecu.

I checked to make sure my map and tps sensor weren't plugged/reverse. I reversed them just to ensure and when i did, the car won't fire up but as soon as i let the key go it would die.

 

Update:

I reset the ECU again for about two hours. Took the car out for a test drive expecting the 3Krpm rev limit but now it's gone. I still have my check engine light for IACV, which I know I still have to get around fixing. However, when I drive the car, the throttle response is very unstable. It's almost as if it's fighting with me on response.

The car and engine jerk a lot when I try to throttle it. I have to keep depressing the clutch to mitigate that issue. This happens on the lower gears (1-3). Once I am cruising above 40mph or so, the jerks seem to go away.

I am not sure what it could be yet but I am thinking the throttle cable setup could be the issue because since it has to loop in an upward position, there is tension on the bend of the cable right at the top of the bracket. What do you guys think?

As you recall, the swap is on a 1992 civic hatch (GSR engine). The throttle body being used is a GSR TB as well as GSR for the throttle cable bracket which points upwards. The throttle cable itself is from an LS because it was the engine in the car previously so I figured I could use that.

I am using a skunk2 intake manifold. With that said, I am thinking I have to replace my throttle body, throttle cable and throttle cable bracket from a GSR/LS(throttle cable) to a Type R for all three to make the jerks go away on light throttle. What do you guys think? Do you think this could be my issue?

 

Anyone have any thoughts?

 

Ok, got a bit more info. I was able to get a hold of the guy who sold me the engine. Apparently, the P28 ECU I have has launch control enabled. With that said, my car doesn't have a clutch sensor so I am thinking the rev limit issue and jerking is due to the fact that the ecu is not seeing the clutch sensor for the launch control which is why is jerks a lot at 1500 rpm and hits a rev limit at 3k rpm.

I guess I have three choices: buy a clutch pedal sensor to see if that solves the issue, find a way to hookup the ecu to my computer to go into Crome and disable launch control, or get a virgin p72 ecu. What do you guys think? Suggestions?

By the way, my check engine light is still on with code 14 IACV. I replaced it with two other working onces and still the same issue. Replaced the TPS with two others ones I had and still had the same issues and all TPS' were calibrated at .5v closed and reads up to 4.60 and WOT. This is probably unrelated to the jerking but I still can't clear that code even by resetting the ECU.

To add to this, I tried my LS ecu and I have no jerk issues at all. What do you guys think?

 

just get a p72 and call it a day

 

I would except that the map on this computer could be a really good map (i haven't verified). It was tuned for skunk2 intake manifold, headers, intake and exhaust. Going to stock P72 might take away some numbers (again, I haven't looked at the map yet to verify).

 

Fix the damn IACV! Common sense

 

If you read my previous posts, I replaced it twice and still throwing a code. Code 14 doesn't necessarily mean it's the IACV. It could be vacuum, tps, iacv, air in the cooling system (all which I have tried resolving but still getting the damn code 14)

I just checked the Crome forum and they mentioned that it does not need the clutch input for two step / launch control so that isn't the problem.

 

Someone from PGMFI.org pointed a new suggestion, which lead me to my finding and thought I would share:

WOW!! I could not help but to check tonight. You got me thinking about those wires. So, apparently, I had the wrong connector to the IACV, which explains why the new swap inherited the same issue. Here is what probably happened. The engine harness for that car had a lot of connectors that were loose and ready to fall off. I fixed the obvious ones through inspection. Since the LS didn't require the purge solenoid connection, the wire connector clip was just hanging (I didn't know that). So, I am assuming that some time ago, the real IACV connector broke off and I didn't notice it broke off so when I was changing the head gasket about a year ago, the only remaining visible connector was for the purge solenoid so I assumed it was the correct wire/connector because one of the wires for it is also yellow/black just like the IACV wires where one of them is also yellow/black.

In other words, the broken connector for the IACV went unnoticed because it sleeved itself back into the wire-loom of the engine harness during the head gasket replacement leaving just one connector exposed, which turned out to be the purge connector clip in which one of the wires is also yellow/black (which can trick you into thinking it is the IACV connector)

It's late in the night to fix but I am positive this is the issue. I will fix this tomorrow and HOPE/PRAY that when I fix this and the CEL goes away, that the chipped ECU doesn't still have that 1,500 RPM jerking issue.

I will keep you posted.

 

OK, that was it!!....the broken wires that were just hidden were actually part of the missing clip from the IACV...that solved ALL issues: bad idle, check engine (code 14) and rough and violent jerks of the engine. The car runs strong and very, very smooth!!! Another successful swap (after so many years) :D

Thank you all for the help