[devtec]

Hey all,

I've been battling with this problem for over a year following a Type S motor swap (35k on the engine). Engine went in with 113k on the chassis, which is now at 129k. Problem started within 250 miles of the swap. Although I still have the problem, I hope I'm close to curing it, and hopefully this can serve as a useful troubleshooting guide for others.

Specifically, these are the symptoms I get:

1. slight stutter on partial throttle under load around 2-3k mostly while lightly accelerating from a stop

2. slight hesitation when upshifting as I apply gas leading to jerky shift

3. an occasional blip where the engine cuts out while cruising at low rpms.

4. general loss of power at low rpms <4k

5. very mediocre fuel economy, getting about 22-23 combined (20 city, 29hwy)

Right after the swap when the symptoms were at their worst, the stuttering was so bad that the car would be jerking down the street while trying to accelerate, and I was getting about 15mpg. Now it is as described, but still an annoyance since the car is not very enjoyable to drive with the occasional blips and loss of power. Throughout all this, WOT seems to have been ok, with car dynoing at 190hp/147tq on a dynojet. Applying throttle aggressively, there is no stuttering. Also symptoms occur irrespective of engine temperature.

I've spent a small fortune trying to troubleshoot this, all of which have led to minor improvements but none of which have solved the problem.

Here's what I've done so far:

ENGINE:
-Compression: tested fine
-ECU: tried USDM ecu, JDM ecu, and a tuned P72 with Hondata S200, none solved problem
-Valves: adjusted, all clearances in spec
-Sensors

o Knock sensor: replaced
o MAP sensor: swap with known good sensor didn't help
o TPS sensor: replaced, and temporarily solved problem, but came back after about 5000 miles
oCPS? - may try if all else fails
oO2 Sensors: both replaced, no difference

COOLING:
-Thermostat: replaced
-Coolant temp sensor: replaced

ELECTRICAL:
-Spark plugs: NGK platinums, coppers, no difference
-Wires: replaced with NGK and MSD, no difference
-Distributor: replaced, lessened stuttering for a few thousand miles, then came back
-Distributor cap/rotor: replaced
-Timing: checked, set at both 16 and 18 degrees, no difference
-Ignition coil: replaced
-Igniter?
-Ground wires: custom kit installed, no difference
-Main relay?

AIR:
-Filter: K&N cleaned
-Vacuum lines: checked
-PCV valve: replaced
-EGR valve, intake ports, throttle body, IACV all cleaned
-Air temp sensor? - will try, this is cheap
-Catalytic converter: replaced with high flow, no difference

FUEL:
-Fuel filter: replaced
-Fuel injectors: cleaned and balanced
-Fuel pump? - will replace next
-Fuel pressure regulator?


So there you have it. Crazy eh? Tried almost everything.

My plan for next steps will be install Walbro fuel pump, replace air temp sensor, replace EGR valve (not just clean), replace CPS. Hopefully it will be the fuel pump.

Would any appreciate any fresh ideas...

Thanks.

[toast]

I am confident that you will end up with a "new" car by the end of this ride.

I read in the Helms that there are no timing adjustments and that the ECU is responsible for timing.

Try a different ECU that matches the block.

[PearlWhitePrelude01]

I had this same problem and replaced the TPS, and fixed it for a few thousand miles. I then tried multiple things like you are. Eventually I found a cheap Throttle Body and that fixed it for the last 25,000 miles until I sold it.

[boost2g]

I just zip tied the runners on the intake open, still have a hint of hesitation under 2k and at wot. Im ready to sell this car now and get a g35 or something else.

[devtec]

Originally Posted by PearlWhitePrelude01

I had this same problem and replaced the TPS, and fixed it for a few thousand miles. I then tried multiple things like you are. Eventually I found a cheap Throttle Body and that fixed it for the last 25,000 miles until I sold it.

Pearlwhite, what was wrong with your original throttle body? Did you replace it with a stock TB?

[gillywig2]

I had the same problem as PearlWhitePrelude01.
I brought a TPS from Omnipower? on ebay. It took a while to adjust but seemed to work for a few weeks then the problem returned. In the end I brought a new throttle body and have had no problems after 30,000 miles.

[BBSix]

I have this same annoying problem, but mine seems to be when my car is warmed up it would stutter for a short period of time and then go back to normal

[LOL_RICE]

Mounts for the bad shift
Fuel pump for anything throttle related

Two parts that actually have the 100k+ miles on them and associated with the cars performance.

You already did half of what I would have suggested :/

[PearlWhitePrelude01]

Originally Posted by devtec

Pearlwhite, what was wrong with your original throttle body? Did you replace it with a stock TB?

Nothing was wrong with it I still have it in the garage. I just found one for decently priced and bought it. Because my Blox TPS would have a dead spot with the multimeter. And I bought it BRAND NEW. So I found a good deal on a throttle body and bought it. Worked fine until I sold it.

[devtec]

Thanks for responding Pearl. So you are essentially saying that it's not the actual TB, it was the TPS that came with the TB you bought?

If I understand correctly, you are saying that your Blox TPS, even though bought new, had a dead spot on it, so buying your new TB with its new TPS solved that problem?

I wonder if these aftermarket TPSs are the problem? I put in a new Omnipower TPS. Fixed the problem for 1 tank, then the car totally bogged down at the end of that tank--to the extent that I even thought I had a flat. Well there was not flat. So I bought a second new Omnipower TPS and put that in. Sort of improved, but essentially led to the current description of my problems.

Does it help to have specifically a Honda OEM TPS that you can only get on a new TB?

[PearlWhitePrelude01]

Originally Posted by devtec

Thanks for responding Pearl. So you are essentially saying that it's not the actual TB, it was the TPS that came with the TB you bought?

If I understand correctly, you are saying that your Blox TPS, even though bought new, had a dead spot on it, so buying your new TB with its new TPS solved that problem?

I wonder if these aftermarket TPSs are the problem? I put in a new Omnipower TPS. Fixed the problem for 1 tank, then the car totally bogged down at the end of that tank--to the extent that I even thought I had a flat. Well there was not flat. So I bought a second new Omnipower TPS and put that in. Sort of improved, but essentially led to the current description of my problems.

Does it help to have specifically a Honda OEM TPS that you can only get on a new TB?

Exactly. Altough my Throttle Body that I bought was not new. It only came with the TPS. I dont know the mileage that was on it, but it definitley wasn't new. So yes, I bought a used throttle body and made sure it had an OEM TPS which it did, and that solved my problem for the last 25,000 to 30,000 miles.

[Vosoka.com]

i herd on honda tech that a V-AFC Controller will solve all your problems & you can hit vtec at idle lol

[LOL_RICE]

Originally Posted by Vosoka.com

i herd on honda tech that a V-AFC Controller will solve all your problems & you can hit vtec at idle lol

Go fail somewhere else.

[97preludeh22]

my car does the same thing i wish i could fix it

[devtec]

Based on replies in this thread, I went ahead and replaced my Type S throttle body with a used 45k mile S2000 throttle body containing Honda OEM Map and TPS sensors.

It appears to have solved the problem. No hesitation or stumbling, smooth acceleration, a huge difference in daily driving. Some return of low end grunt.

So let's see how it goes. After all I've been through, I am remaining skeptical and will wait a few tanks or thousand miles before making a conclusion. But the car is once again a pleasure to drive. For those wondering, the S2000 throttle body is the exact same dimensions (68mm --> 63mm) as the Type S throttle body, just without the IACV.

Will keep this thread updated. If putting a Honda OEM TPS does indeed solve the problem, then I will start another thread strongly recommending against purchasing the Omnipower TPS, it having failed on me twice.

[devtec]

Also, I do still notice just a bit more power when the tank is full, so suspect a weak fuel pump. Will replace this soon and report back.