Installed exhaust, interesting symptoms.

[TheAmazingDave]

I installed my 3" downpipe and my 3.5" cat-back over the weekend. The car sounds wicked now, but when I floor it, after the turbo spools it feels like power is fading out, then it comes back higher in the revs.

I have two theories, but I don't know how accurate this is. I'm thinking that there may be some detonation when boost hits and the knock sensor is causing the ECU to pull back timing, or the automatic is slipping under the sudden power.

I'm going to fill up with a blend of 100 and 91 octanes tonight to see if that helps, but I was hoping some of the experts here may have some advice.

 

[GotToyota?]

I'd suggest putting in a good synthetic (ex. Royal Purple, Redline) tranny fluid from here on, to prevent your tranny from slipping.

-Matt

 

[loki2043]

mods?

 

[TheAmazingDave]

Simple BPUs.

K&N intake, HKS SSQV recirculated, MBC set at stock boost (aftermarket gauge hits 7 PSI), 3" Titan downpipe, 3.5" Blitz Nur-Spec cat-back.

 

[lagged]

go for a run then read your plugs.

its possible that your fuel pump may be on its way out, it happend to me.

 

[Nick M]

Besides the other things mentioned, we can eliminate the transmission if your engine speed is not picking up. If the engine speed increases, and the vehicle does not, then you have a slippage problem.

 

[robbo185]

try resetting the ecu. Its usually a good thing to after you mod the car because a change in anything will mean the old fuel maps will still be applied to the old setup

 

[lagged]

try resetting the ecu. Its usually a good thing to after you mod the car because a change in anything will mean the old fuel maps will still be applied to the old setup

ehh i dont know how accurate that is. any TCCS experts care to chime in?

 

[Nick M]

Pulling the EFI fuse will change fuel trim, but that is going to happen anyway. Short term fuel trim is what is used to modify the long term.

Pulling the EFI fuse never fixed a car for me. I always had to do something else first.

 

[TheAmazingDave]

Well, I mixed 6 gallons of 100 octane to 3 gallons of 91 and the issue remains. I don't know how much 91 was left in the tank when I filled it, but the gauge was a hair above the E line.

When it happens, the car's acceleration slows, and the engine speed holds the same for a few seconds. The car is still accelerating slowly when the engine holds. So, revs will climb to about 3-3.5k quickly, then stop, then it starts reving again.

My narrowband A/F gauge shows rich when it happens, but not full rich.

 

[Nick M]

Engine load increases, fuel enrichment happens as expected, and power is lost. Take a look at how good the spark is. I didn't see very many bad coils at Toyota, but it could happen.

 

[TheAmazingDave]

I believe it has the original Toyota platinums in it. If Toyota didn't change them at 35k when they did the head gasket and shortblock, they should be due for a change as they'd now be at 62k. I'll pick up a set tomorrow. Hopefully that will help out.

I take it there's a test procedure for the coil packs in the TSRM? I'm gonna go dig it out and check.

 

[TheAmazingDave]

Well, I fixed the power issue I believe. I took it for another drive and I kept a close eye on my gauges. I found that I was at 18 inHg at idle when I was at 20 yesterday, also my A/F gauge showed slightly leaner at cruise that it did before. So I stopped and checked all of my hose clamps, and I had left the BOV-to-3000 Pipe coupler loose. After tightening it I gained 1 PSI at full boost and the car is now stupid fast.

But it definately seems like the transmission is slipping, or perhaps it's the torque converter shifting to full lock, IDK as this is my first automatic car. The revs still shoot up pretty quickly then stop. But now the car is still pulling like mad when the revs stop. After a second the revs start climbing again.

I'm going to switch it to a better fluid when I change the spark plugs, hopefully that will help a bit. If not, time to start researching a manual swap. :naughty:

 

[starscream5000]

Does it feel choppy at higher RPM's? Is the MIL light coming on?

 

[TheAmazingDave]

Does it feel choppy at higher RPM's? Is the MIL light coming on?

no, still very smooth, no CEL. I haven't checked for stored codes yet.

 

[BorHor]

When it comes time to 5 speed swaping call me up I will be down for helping.

 

[TheAmazingDave]

I bought 8 quarts of RedLine Dexron II. I gotta read my TSRM again on how to drain the torque converter, I'll work on that later tonight after work.

Toyota didn't have plugs in stock so I'll have to order them, but at this point the power is there and very strong, so I'm ruling out fueling and ignition issues for now. I got a new Toyota oil filter and a case of Mobil 1 10-30 to put in tonight as well.

 

[theKnifeArtist]

Does it feel choppy at higher RPM's? Is the MIL light coming on?

what does that mean..because i've gotten that.

yeah and my auto slips from 1st to 2nd..it sucks big nuts. it makes my rear end swing out all the time.

also..3" downpipe and 3.5" catback? isnt the dp bottlenecking the 3.5" catback? someone explain please, thanks.

 

[TheAmazingDave]

what does that mean..because i've gotten that.

yeah and my auto slips from 1st to 2nd..it sucks big nuts. it makes my rear end swing out all the time.

also..3" downpipe and 3.5" catback? isnt the dp bottlenecking the 3.5" catback? someone explain please, thanks.

A small bottleneck, the 3.5" is still going to help releave some of the pressure in the 3" downpipe i would think, but I'm far from a physics expert.

Besides, the 3" downpipe barely fits. A 3.5" would be a very tight squeeze.

 

[gilberjj]

3" is plenty big for your mods and power. 935 motorsports was telling me that a guy dynoed in the 500's range, thought his 3" exhaust was restricting power, so he switched to a 3.5" exhaust and gained 13 rwhp. 3" flows well.