really hard to start after replacing cam and crank sensors

[daedaestoy]

i had my 02 jeep rene 3.7l start missing on me 2 saturdays ago very badly to the point that every time i slowed it stalled... i had hoped it was just a faulty coil pack again.. but turned out to be a dealer code that said there was an error with the communication between the cam and crank sensors so i figured that one of the sensors were failing so i jus went ahead and bought both sensors since it was only like $30 for both and figured it would fix it... it runs flawlessly now but wont start sometimes.... very difficult to get it to start in the morning or once its cold... but once it is warm it is fine till it gets cool again... anyone experience this problem before? or can point me in the right direction to fix this because it is for sale and would hate to loose a sale because it wont start correctly and it turn out to be something simple... any and all advice is and will be appreciated thanks guys..

 

[daedaestoy]

no help at all....

 

[diyman]

OK. We all know we're talking about the 'most likely' cause....

I inferred sensors are OEM....

Failing ECT sensor might be a possible cause. The engine would be getting the wrong 'mixture' thus possibly causing hard starting.

But who knows, even TPS going south might not help. Injectors??? They'd probably cause rough idle too.

I'll take for granted that spark plugs and air element are OK.....

 

[daedaestoy]

OK. We all know we're talking about the 'most likely' cause....

I inferred sensors are OEM....

Failing ECT sensor might be a possible cause. The engine would be getting the wrong 'mixture' thus possibly causing hard starting.

But who knows, even TPS going south might not help. Injectors??? They'd probably cause rough idle too.

I'll take for granted that spark plugs and air element are OK.....

yes the spark plugs and air filter were new when the motor was built about 6k miles ago... i think it would be weird that all 3 sensors went bad at the same time? but hey what do i know? as for the TPS it only runs bad on start up and cold once it is started its completely fine starts fine and runs flawlessly as i had said before.. i have had the codes read a few times and it keeps comming up with a random misfire code... not a certain cylinder...

 

[diyman]

Sorry, but, don't mean to contradict... You say engine runs smooth while giving out a multiple misfire code ?!

How is idle after start-up? Remains the same? Varies a lot?

If You can, borrow a good scan tool with live data funcion ( most do ), connect it to the port but don't start the engine.

See if the coolant temp. is close/same as room. If so then ECT should be ok.
Check out throttle pos. data, by pressing the pedal and see if it changes reasonably. If so then it's ok.

If idle remains 'high' then possibly IAC is dirty... See 'how to' for cleaning....

Misfires are a PITA, but check fuel system( delivery and injectors), air leaks and cat ( plugged?).

Many disagree, but I trow a can of injector cleaner every now and then, and it has always worked for me.