After 5000 rpm Car holds hack power

versatilx1 · 11-05-2009, 07:01 PM

I just replaced the knock sensor and o2 sensor. Car runs good, but when i start to get up to 5000 Rpm it cuts back on power, like it doesnt want to go past it and feels like it bogs... I was thinking a possible boost leak somewhere. No check engine light and this is my 1990 EAGLE talon AWD TSI Mods=HKS Full Catback and thats it.

boostedjay32 · 11-05-2009, 07:05 PM

If u have the. Stock turbo those don't hold boost pat 5k

4g63awdhonda · 11-05-2009, 07:17 PM

Could be a boost leak, also could be picking up knock around that rpm..

Do a basic tune up on the vehicle and see if that helps anything!

zhjiln · 11-05-2009, 07:17 PM

well just log the car and see what is going on in there...

also could be your wires and plugs breaking up in the higher RPM ...

versatilx1 · 11-05-2009, 07:33 PM

I want to say a boost leak and i have a slight air leak by the exhaust manifold... Ill tune it up, but i got no check engine light if i had knock i would get a check engine light right?

GooeyGus · 11-05-2009, 07:55 PM

Quote:

Originally Posted by versatilx1

I want to say a boost leak and i have a slight air leak by the exhaust manifold... Ill tune it up, but i got no check engine light if i had knock i would get a check engine light right?

knock wont throw a CEL (at least on a 1g)

I think the only time it will throw a CEL is if it senses knock and then encounters a problem while trying to retard timing (dont quote me on that, I got the info a while ago and cant remember it verbatim).

BUT I do know for sure that knock usually wont throw a CEL. I have really bad lifter tick at times, and the knock sensor picks it up and I can feel the ECU pull timing (feels like someone attached a bunjee cord to my car... it still revs but just feels like it's not accelerating as fast as it should. This is only while cruising BTW... as soon as I pass a certain RPM the lifter tick stops and I can feel the car come alive again)

Do you have a boost gauge? Is it holding steady even when the power drops?

Does the drop of power happen smoothly, or does the car buck or sputter like a cylinder dropped out?

versatilx1 · 11-05-2009, 11:51 PM

A knock will throw the CEL light on. Especially if the sensor is malfunctioned. And yeah im gonna hook up my gauge tommorow and see what happens and put it this way when i get up to about 5k rpm it feels like the car is holding back.

GooeyGus · 11-06-2009, 10:14 AM

On obdII it might throw a CEL, but I'm pretty sure that knock will not cause a cel on a 1g. This is why people rig up a "knock" LED to the BCS, because there is no other indicator that the ecu has detected knock.

Again, I could be wrong but I've logged knock about a million times without a CEL.

spawn87 · 11-06-2009, 12:24 PM

well since your car is an awd it makes scene ... dsms like the 1g and 2g (awd models) have more drive train lost in power and since the 4g63t motor gives maximum tourque at 5k and the t-25 stops producing power at 5k also... you simply running on hp that is not enough to get all those parts moving at same rate.

when i first switched to awd i notice this too and was freaked but the more research i made it made scene

solution: bigger turbo fuel system and support mods

versatilx1 · 11-06-2009, 04:00 PM

Ok update on this problem.. As i was driving i noticed its not always at 5k rpm its just whenever it goes from 7 to 14lbs of boost.. it starts to "Miss" or feels like it doesnt want to go and i have to let off. If i go WOT and it climbs to 7into14 its all bad.

GooeyGus · 11-06-2009, 04:25 PM

Quote:

Originally Posted by spawn87

well since your car is an awd it makes scene ... dsms like the 1g and 2g (awd models) have more drive train lost in power and since the 4g63t motor gives maximum tourque at 5k and the t-25 stops producing power at 5k also... you simply running on hp that is not enough to get all those parts moving at same rate.

when i first switched to awd i notice this too and was freaked but the more research i made it made scene

solution: bigger turbo fuel system and support mods

the car should be able to rev past 5k with no problem, AWD or not.

natertater · 11-06-2009, 04:39 PM

fuel issues? and by 7-14 psi, you mean stock gauge? dont trust that one bit...

spawn87 · 11-06-2009, 11:29 PM

Quote:

Originally Posted by GooeyGus

the car should be able to rev past 5k with no problem, AWD or not.

never said the its normal for car to not rev past 5k i said i does not run as quick as the initial boost pull past 5k.

Quote:

Originally Posted by natertater

fuel issues? and by 7-14 psi, you mean stock gauge? dont trust that one bit...

+1 on that those gauges are garbage go get your self an after market one.
go a boost leak test and check plugs and wires might be time to change them.

Spoolin4Ever · 11-07-2009, 01:53 AM

The DSM Doctor Prescribes 4 NGK Copper Spark Plugs and repost in the morning.

Repeat every 6 months.