osb

well i have a hesitation problem around 3 to 4000rpm and again at higher rpm

it only occurs when im at 1/2 or more throttle

my engine is newely rebuilt
like 10k on it, new plugs.. new wires on saturday and a fuel injection cleaning.. i have read many different fixes for this problem i dont know which ones to try first...

any suggestions

-- osb

vaughnc

It's probably the typical 3800 rpm hesitation/grounding bug or you intake system (metal manifold or plastic tubing) is leaking air and freeking out your o2 & other sensors causing the car to sputter.

seveninphilly

iTrader: (7)

here is what I just went through

https://www.rx7club.com/forum/showth...highlight=3800

start with the simple stuff

Oh to start if you have a multi meter check your grounds from black wire on boost sensor should be less than .5 ohm to frame
battery ground should be less than .5 ohm to frame


3800 RPM Hesitation Fix (Dana Sullivan)

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This is supposed to look like the plug that connects to your boost sensor. Take the plug that has a brown (upper left) wire leading into it and run a ground from it to bare metal, try the radiator filler neck.

1) Locate the boost sensor on the front of the passenger's side strut tower. Note: There is a vacuum line running from the sensor to the side of the engine block.

2) Disconnect the 4-wire 'gang plug' from the sensor.

3) Locate the upper left wire. Refer to diagram.

4) Take a very small flathead screwdriver and insert it into the back of the plug on top of the wire. You should be able to raise a small flap of plastic allowing the brown wire with it's crimped connector still attached to be removed from the gang plug.

5) Take a 12" piece of thin gauge wire and solder one end to the connector where it is crimped around the brown wire.

6) Insert the crimped connector with the new wire attached back in the gang plug.

7) Loosen one of the bolts that holds the radiator cap housing to the filler neck. Strip 3/4" of wire off the end of the ground wire your just soldered and wrap it around the loose bolt. Tighten bolt.

8) Plug gang plug back into boost sensor

EDITOR's NOTE: This fix is NOT guaranteed, it seems to have about a 50% chance of solving your problem. It does NOT work on my 1987 Sport, but others have had success with it. I personally do not think this is the cause of the problem. I believe, partially because it worsens in low temperatures, that it has to do with wear on one or more other components, or a programming error in the engine management computer. I happen to know of one 1987 GXL of a newer build date than mine which does not suffer from this problem. I believe that the problem may be caused by progressive failure of the exhaust system. I think that as the exhaust gets older and the front cats start to disintegrate into the main cat backpressure increases, causing the ports to open early or late. When I replaced the cats on my car with a downpipe and presilencer from MazdaTrix the problem promptly vanished.

Ni5mo180SX

The fix to my hesitation involved cleaning out the actuators.

osb

havent had any luck so far yet.. but i know 1 thing, when i put my car on a lift and put it in the air most of the exhaust was rusted out and holey,, this is prolly my problem right here, eh?

Icemark

Well you will have intermitent or complete lack of 5th/6th port operation if the exhaust has too many holes in it.

Thaniel

Found my hesitation saturday (high rpm not at 3800). Turned out the orifice in the boost sensor line disappeared. Probably happened when I cut the cracked end off the line. Didn't know one was there at the time. Anyway put in an orifice and it is good to go again.

'86 N/A