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Will a 4.0 run without a knock sensor?

D

dtmracerx

NAXJA Forum User
Location
Wisconsin
I am nearly done with my engine swap and I think I have everything connected, but when I try to start the engine It cranks but never "catches"

There are three thinigs that i am currently aware of. 1) The Knock sensor has completely destroyed on both engines so I currently do not have one hooked up. 2)Fuel line leaks so there probably isn't correct pressure at the injectors. 3) the only vacuum lines I have connected are for the MAP sensor and fuel pressure regulator all others are blocked or capped. Is there some crucial electrical/vacuum unit that i need plumbed in?

I am at witts end after 3 weeks of freezing my ass off getting these engines swapped around, and I have $500 worth of brand new tires waiting for the beast to roar to life...this has been an exhausting project.
-G
 
This is a RENIX, correct? You do not need the Knock sensor to get it running and if you use good fuel and keep it tuned you really do not need it at all.

Have you had the distributer out? if so it could be indexed incorrectly.

Is the CPS a good one?

Check your grounds!!!! That will stop a RENIX in its tracks. The one that goes from the firewall to the manifold is usually the culprit.
 
Something else that I forgot to mention is make sure that the fuel injectors are hooked up to the correct wires, #5 and #6 are easily mixed up. I don't have the wire colors in front of me for the RENIX, its in my Jeep but maybe 5-90, Langer, or Old Man will post up the color chart.
 
dont need a knock sensor. id have to take a stab at and say its a crank shaft sensor. but without doing a few tests you cant be sure of it. The first thing i would do is see if you have spark. if you have spark the next thing i would do is check the fuel pressure at the shrader valve. if you have both of those, then that leads to some sort of a sensor ( in my personal experience ) which would be the crank sensor. havent had trouble starting my renix if the vacum lines werent hooked up. i would also check your connections at the starter relay by the battery and i would double check all grounds as well.
 
Well heres the beef on my grounds:
WHen trying to remove the bolt from the passenger side of the block i could not separate it so i cut all the wires.
When reassembling the wiring I put the battery ground on a replacment bolt in the same location but ran the other 4 (hopfully thats all of them) small wires to the firewall where I could get at them. Do those 4 perhaps need to be connected "better"? I was assuming they had something to do with the DME but was unsure. (I did this whole swap so far without having my own repair manual...isn't that sad? no wonder it isn't running yet!!)

Thanks jordo for the wiring; I will have to check tonight!

-G
 
dtmracerx said:
Also- how do you identify the RENIX system?
:)
-G
Click to expand...

What year Jeep did the engine come out of, and what year jeep are you putting it in to?
 
99XJSPORT06 said:
What year Jeep did the engine come out of, and what year jeep are you putting it in to?
Click to expand...

The engine is out of an 89 cherokee. going into an 88 comanche. all sensors etc hooked up to the old harness so they are obivously the same system. (the wiring harness itself is slightly different between the two...but all connectors were the same)
-G
 
dtmracerx said:
The engine is out of an 89 cherokee. going into an 88 comanche.
Click to expand...
It is a RENIX (Renault-Bendix). If you don't have spark, the most likely culprits are the ignition control module (ICM) or the crankshaft position sensor (CPS).

The ICM sits under the coil, 1 connector and two bolts take it right out and most parts stores (Checker, Autozone, etc.) can test it for you.

If that isn't the problem, search for the threads on checking and changing the CPS, not expensive, but a pain in the behind to change.
 
Is the CPS the sensor bolted on the tranny bellhousing? 'cause if that is the culprit i will be so pissed...after having the engine out last week...

BTW- does anybody know what kind of trigger the RENIX uses for the crank? and is there a camshaft position snesor as well? I would be very interested in converting to a programable engine computer at some point if the OEM sensors support it.
-G
 
There is a Synch Sensor inside the distributer, but they rarely go bad. If it is bad you can replace the whole distributer from Advance Auto for $50.

Are you testing this stuff or just grasping at idea's? You really need the RENIX service manual to test each and every thing. Only test equipement you will need is a volt/ohm meter.

Check your PM's
 
I will be checking things as soon as I get my fuel Orings from my local chrysler stealer...er....dealer.

One thing I know is that between my two engines I have a working sensor for everything (other than that stupid knock sensor) since both engines ran before this whole "event"
 
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