Imrc
03-31-2013, 05:50 PM
#1
Member
Thread Starter
Low power at wot
Couple questions to help me track down my low power issue. (2004 5.4 3v)
Condition 1: Under heavy load and WOT I could feel a power reduction at slightly above 3000rpm. Feels like can't get enough air. No codes. IMRC was replaced a few months ago by dealership.
Question 1. What monitors the position of the intake runners and is it possible they are working backwards?
Condition 2: Barometric reading on scanner is 145hz. For local altitude should be 156hz. Also MAF readings are way low at higher rpm. Max reading I got was 15lbs/min or 113g/s. Should flow about 200g/s. MAF was swapped out with one from good running truck with no improvement.
Question 2. Is there a separate baro sensor or is it built into the MAF sensor?
Dealership gave up trying to fix so I have no other source to troubleshoot this issue. Not a happy camper.
I've posted several times with this issue with little response so it must be a stumper...but I will keep trying.
Thanks for any help.
Jeff
Condition 1: Under heavy load and WOT I could feel a power reduction at slightly above 3000rpm. Feels like can't get enough air. No codes. IMRC was replaced a few months ago by dealership.
Question 1. What monitors the position of the intake runners and is it possible they are working backwards?
Condition 2: Barometric reading on scanner is 145hz. For local altitude should be 156hz. Also MAF readings are way low at higher rpm. Max reading I got was 15lbs/min or 113g/s. Should flow about 200g/s. MAF was swapped out with one from good running truck with no improvement.
Question 2. Is there a separate baro sensor or is it built into the MAF sensor?
Dealership gave up trying to fix so I have no other source to troubleshoot this issue. Not a happy camper.
I've posted several times with this issue with little response so it must be a stumper...but I will keep trying.
Thanks for any help.
Jeff
Last edited by Jeff_B; 04-01-2013 at 05:40 PM.
04-01-2013, 01:00 PM
#2
Member
Thread Starter
IMRC and Baro Sensor
Any ideas at all guys? Really need help....
Is there a separate Baro sensor aside from the MAF?
Is it possible to hook up the IMRC linkage backwards? (it so hard to see back there)
What actually senses intake runner position?
Thanks!
Is there a separate Baro sensor aside from the MAF?
Is it possible to hook up the IMRC linkage backwards? (it so hard to see back there)
What actually senses intake runner position?
Thanks!
04-01-2013, 05:50 PM
#3
Senior Member
Have you checked for clogged CATs? Try dropping the exhaust. Remember and engine is an air pumpif it can get it out than it can't suck it in............ Also are you on stock air box cleaner and fliter or aftermarket "performance" one?
04-01-2013, 08:01 PM
#4
Member
Thread Starter
The dealership told me same thing so I had the pre-cats cut out and new ones welded in at a local muffler shop to the tune of $700. Both the dealership and the muffler shop have done backpressure tests afterward and both say flow is fine. Vacuum is 20 at idle. Intake and filter are stock.
Conversation at the dealership this afternoon confirmed that the Baro is a calcualtion based on readings from the MAF. They also said that the position sensor for the IMRC (or CMCV) is built into the actuator.
I found a post on another forum where a guy installed a new actuator and stated it was "backwards of the original and followed the included instructions" ~ paraphrasing~ So it appears that it is in some form possible to get things reversed. I'm not getting codes though. I would think that if the runner butterflies were working backwards I would have a rich condition....
thanks for ideas!! Jeff
Conversation at the dealership this afternoon confirmed that the Baro is a calcualtion based on readings from the MAF. They also said that the position sensor for the IMRC (or CMCV) is built into the actuator.
I found a post on another forum where a guy installed a new actuator and stated it was "backwards of the original and followed the included instructions" ~ paraphrasing~ So it appears that it is in some form possible to get things reversed. I'm not getting codes though. I would think that if the runner butterflies were working backwards I would have a rich condition....
thanks for ideas!! Jeff