Started running rough, think its the Cat...

[mossman65]

Good Morning Everyone and thanks for having me!

I have a 98 Ranger 4cyl Vehicle has bad hesitation when accelerating from a stop. Sometimes if I accelerate slowly the hesitation is not as
Bad. Does not seem to hesitate as badly when you Accelerate while already moving at highway speed.

I tried seafoam through the break booster lines and that didn't help. Has anyone else had this problem?

Thanks!

 

[RonD]

Clean the MAF(mass air flow) sensor.

Use Seafoam in the gas tank to clean injectors.
Seafoam in the intake cleans carbon from the cylinders, carbon build up causes pinging/knocking not hesitation.

Clogged exhaust causes limited RPM range, as you accelerate, RPM increases, a clogged exhaust causes a build up of back pressure so new air/fuel mix can not enter the cylinders and power drops off, it doesn't get better at higher RPMs, it is like hitting an RPM wall, engine simply can not rev above a certain RPM based on the blockage.
i.e. the old potato in the tail pipe trick, total blockage, engine will start then die, then won't start at all until pressure leaks out

 

[mossman65]

Hi Ron,

Tried the MAF and that wasn't it. Another item i forgot to mention, when you first start it runs good until it starts to warm up. Any other thoughts? Thanks you very much for your time!

 

[Starlord]

Try the spark plugs and coil. Sounds odd but my 99 F150 had the exact same symptoms. Ran perfect until warmed up, then just dogged on acceleration. I changed my coils and plugs and it ran like new (after my changing fuel filter and cleaning the MAF, which did nothing). Could start with just the plugs. May not be it but they're cheap enough. Fuel filter would also be an idea. Somebody suggested my Crank sensor if the plugs didn't work, obviously I didn't have to do it but also an idea.

 

[mossman65]

Thanks Starlord i'll try that and let you know!