Thread: Power loss at WOT in the mid range upwards

I'll try to give as much info as possible here but before I go any further I thought i'd ask on here.

93 N14 GA16DS, i've swapped in a 10:1 highport SR20 out of an N14 GTi. So because this was carb and i've gone to injection i've had to swap the fuel tank as the injection sender unit/pump holder wouldnt go into the GA tank. I also noticed that the hard pipes and hoses were a smaller I.D so i swapped those too. Took pretty much everything like for like off the GTi and into my car. Didnt take the interior harness out as that was too much of a chew on. Spec is nice an simple, SSAC 2.5" into a custom 2.5" mandrel system. Does have a rather ghetto intake hose with the idle control valve sort of pushed into a hole i cut into the hose. The side breather pipe that normally goes into the intake pipe is just hanging, the air filter itself is fairly new and very clean (quickshift I think it is) the fuel filter is fairly new also. There is no O2 sensor hooked up. Removed EVAP system, blocked vac hose on TB, left hose back to the tank vented under the car. Havent done a fault code check as the consult plug is different on my car to the GTi so I cant do one (unless theres any other way to do it?)

Got the car up and running great, was a bit lumpy and jerky so I did usual tune-up fixes, so far i've checked timing, its at around 15, set TPS to 0.5 closed and 4.0 at WOT and reground and cleaned MAF , that made it much nicer to drive.

Now my main issue is when I floor it, it picks up lovely up to around 4500rpm and it feels like it loses around 100hp as it keeps revving but with a great loss of power, almost like its really strangled, its not a little missfire, it just gets to that rev range and just says no all the way to the limiter.

Now at the moment I have the fuel pump hard wired directly to the battery until i wire it up properly with a relay etc, I am aiming towards the fuel side of things as the original pump is still there and the little pre pump filter was blacker than the ace of spades, but at least I know the pump is getting a good feed with it being direct to the battery. Could the pump be breaking down as the revs get higher? could the FPR be a bit sticky? I dont have anyway of checking fuel pressure so I might have to take it somewhere with a dyno so they can check fuel pressure while its under WOT

Thanks for any input

managed to plug my ECU into another N14 GTi today and did a fault code check, code 11. So i swapped the dizzy off that particular GTi, didnt change. Tried the ECU just to rule that out and that didnt fix it neither, so I guess im onto the wiring

The wire you are looking for for the cam position. This one can be messed up and the engine will still run, but its used to determine the engines rpm increase so I can see how it would mess things up on WOT. The other wire is the cam reference and if this wire is messed up the car will not run. So easy way to test it is check for voltage at the wire. Should be about 2.4v. If you have an oscilloscope, you can look at the signal. But one thing to remember is this wire and the reference wire is in a shielded loom and the look is ground to the ecu near the ecu connector on the harness. This shielding keeps both of those signals from becoming distorted due to the harsh environment of an engine bay. Be sure to check all of you ground though. Let us know what you find.

thanks for your reply dude.
I checked voltages at the ECU and yes they were both around 2.6v (within the range on FSM) I checked the plugs out of daftness and it had iridiums in, I swapped them for normal BKR6E-11 and it made the engine much better, the sudden loss of power was now less harsh and it revved more freely but was still lacking power.

Moved to mechanical rather than electrical today and did a compression check. My results were:
140/155/160/165
FSM says if lower than 156 so I guess ive found my problem. Did a wet test on number 1 and it shot up to 240 so its time for new rings, rod bearings and head gasket

Did you do the compression test on a cold motor? Those numbers seem very low across the board. The procedure is to warm the engine to operating temp, turn off the engine and pull the fuel pump fuse. Next press the throttle all the way open and crank until the compression needle stops. Just in my experience, people tend to overlook this.

Don't forget to pull all spark plugs as well before testing

Yeh man i know how to do a proper comp test guys. The car the motor came from was a track car and only a track car for the last part of its life and had 95k miles so im not surprised really.

Car was fully warm
fuel pressure was released fully
all plugs out
battery was good for turning
throttle was open

You can try a leak down if you have a compressor. It will tell you if its the valves or the rings that are leaking