My s4 struggles to get to 20 mph and I hear a clicking clanging noise coming from the engine. When I pulled over to check out the car it smelled like something was burning. I have no idea what's wrong with my car I just got it, and don't want to mess it up. Before I took it out to drive I took off the maf sensor , switched air filters took the exhaust manifold heat sheild off and sprayed engine degreaser over that whole section of the engine and engine bay. . I don't know if what I did may have caused the problem. Any help would be much appreciated. Thank you

 

You did put the AFM back on, right?

You should put the exhaust heat shields back on before you cook everything in that area.

Check the TPS to make sure it is plugged in and test it according to the instructions in the FSM.

Check to make sure the CAS is in the proper position.

Check to make sure the cats are not clogged.

 

yes i put the AFM back on before i went for a drive
cats seemed fine when i checked them, mufflers are rusted but the car still reeks of fumes inside when i start it
i checked the the cas resistance to see if it was bad and i kept getting different numbers from 150 to around 300ohms. should i replace cas or just remove it and adjust the whole timing ?
i tried checking the tps but my meter would not get a reading. i warmed up the engine and opened the throttle valve just as the fsm says but still no reading ? maybe its just my meter .. ill check again today with another meter
also when i go to start my car it struggles to turn over . i turn the key for 2 seconds then hear a whoop whoop noise come from the engine followed by a metallic grind noise as the car buckles down then starts. is this related to the cas?

 

The key needs to be turned to on to get a voltage reading on the Green/Red wire at the TPS.

 

i just tried to check the the tps again with key turned on and still no reading. . i tweaked the adjusting screw also to see if i can get a reading and nothing. . new tps?

 

Are you sure you're checking the Green/Red wire? Are you sure the ECU is powered up properly? There is a B/W wire which runs from the Main Relay to the ECU and this wire powers the ECU. The B/W wire can be found near the leading coil in a four wire Green connector so check this wire w/key to on for 12 volts.
And the "on" position is two clicks after the off position. Off>ACC>On>Start.

 

yea it ended up being the meter i was using was too broad. i got another more specific one and the cas read 128 on both g1/g2 and ne1/ne2
the reading on the tps was 4.20 on a to c and 1250 on a to b
so if the tps and cas check out whats next? should i still take out my cas and redo the whole timing on the car?

 

The G/R wire should measure 1 volt w/key to on. If it doesn't then adjust the TPS screw till it does.

If the CAS/timing was correct before then it should still be correct. If you have reason to believe it has been out of spec then of course retime it.

 

You switched air filters? Did u change the filter or type of filter? Performance you describe sounds like the afm hose is off or one of the large hoses(1") on the bottom of the afm hose is off.

 

Ok I got the G/R wire to measure 1 volt. .but the car will still struggle to get past 20mph and I still hear that clicking metallic noise coming from the engine, the engine feels like its going to pop if I go any faster than 30mph. The reason I suspect the cas to be the problem is because as I took off the heat sheilds I had the car on jacks and when I lowered the car it came down violently on one side. . Maybe that messed with the cas position.? Or something else?

As for afm I've checked it a thousand times. Everything is hooked up and air tight. I replaced the filter with an oem one. No aftermarket stuff

 

Might want to check the plugs on the primary injectors to see if they were rattled loose. Also, can the car rev freely when in neutral? You also might have damaged the cats and clogged them up which could cause the engine to bog down.

 

ok ill check the injectors right now and yes the car revs freely in park and neutral. also i cut my o2 sensor when i was taking off the shields to the exhaust manifold and just twisted it back together and put black tape on it. . could that be messing with the control unit?

 

i also checked the voltage on the black/white wire with the wire below it in the green connector
and got around 8 volts

 

What does "with the wire below it" mean?

EDIT: What does the car idle at rpm wise? The TPS needs to be set when the car is fully warmed up and idling in the 750 -800 rpm range.

 

i was checking the voltage using the black/white wire and another wire that was there in the green connector. . i checked the wire voltage again on the black/white wire but i grounded the other end this time and got 11.83 volts. .so i know thats good now
and the car idles perfect around 750rpm.
the primary injectors were on good also

 

What rpm are you using to get to 20 mph? Is your car an automatic?

You might want to disconnect the TPS plug and also disconnect the vacuum hose from the Pressure sensor and cap it. This will put the car in a situation where the engine will think it's under load allowing you to free rev the car in neutral and it will cause the secondary injectors to come on when the rpm hits 3800 or higher. Normally free reving will not allow the secondaries to turn on.

And when testing for voltage on a wire you always need a ground source for the Black meter lead.

 

its an automatic and the car starts to struggle once it passes around 2500-3000 rpm

 

you live in LA, take it to one of the many rotary shops in the area and have them look it over.

 

i wish it were that easy. . low on money

 

By plugging the vacuum hose to the presure sensor and disconecting the tps and reving the car over 3800rpm . . What will this do? What should I check?

 

I would think it will tell you whether the problem is related to the secondary injectors, TPS or the Pressure sensor. Takes all of a minute to do. You already mentioned that the car free revs w/o problem so this pretty much eliminates the primary injectors so the focus should be on the secondary injectors and or the sensors which help to determine whether they should come on or not.