What would make the rpm jump(flicker) ?

I replaced mass air flow, distributor,optima battery,radiator,exhaust,no leaks on exhaust,just got it put on,new wires,distributorcap ,rotor,iac motor,hoses,plugs nkg v,ignition switch,o2 sensors, egr, engine coolant sensor,always change oil, new short ram air filter,,all new vaccum line hoses, fuel filter, two much money and two many to list. It seems every time I stop or have the ac on Ithe rpm flikers and i feel the engine stutter,till I gun the gas pedal feels sluggish on take off and first thing in morning. I been working and searching on the net and buying parts related to this problem and still no luck. its bugging me and I hate to ask but i dont know what to do. Lat code it through it was p 170 fuel trim malfunction. I traced to mass air filter or exhaust leak i replace maf sensor and today just got my header put on after four months and it still doing that sluggish feel. I replaced the iac motor thinking it was the problem. I' pretty sure its not the throttle position sensor. cleaned throttle body. I 'm clueless any suggestion i'm breaking the bank and no lucjk everthing i changed and replace on car but engine and trans which will be in the future. I do tune up ever since i got it last year. I have come a long way. I love this car to death and have so much work and fun with it. I really enjoy this board and the people on here and its so amazing at what you all do to these cars. I love it. Soory to nag but if you could maybe steer me in the right path again. Thanks!

Looks like you covered a lot of the areas that could be the problem...
I know its natural for rpms to drop a little when the ac is turned on but if the car is also feling sluggish when acellerating, I would check the cap and rotor/sparkplugs and wires...

How is your idle? I would check the egr vacum module thingy's along your firewall as wel... I remeber when my car felt sluggish, these are things I tried...

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Originally Posted by phizzalot

Looks like you covered a lot of the areas that could be the problem...
I know its natural for rpms to drop a little when the ac is turned on but if the car is also feling sluggish when acellerating, I would check the cap and rotor/sparkplugs and wires...

How is your idle? I would check the egr vacum module thingy's along your firewall as wel... I remeber when my car felt sluggish, these are things I tried...

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Plugs,rotor,cap,all fine what lil things on the firewall all vaccum lines are new. I replaced them. The egr solinoid.the red plastic one. i dont know where to get it they dont have then in the auto stores. I cleaned egr valve it works.thanks anyways for the suggestions. nICE RIDE!

try your alternator.... You might want to either upgrade it or get a new one. Im having the same problem with my g.

I just changed the alternator a few months ago.

Do an engine vacuum test. With a fuel trim malfunction it could be vacuum leak causing the pcm to compensate with more fuel, as it adds fuel the rpm will climb, then drop as it realizes that it has added too much fuel.

i replace all new vacum lines on it. seems like might be the throttle position sensor.

let me know if you gonna buy one.

can you do a vaccum test yourself?

i'm probly going to by one at the end of this month or next. tps 130 at autozone. mine has never been changed since i bought car,plus it only has one screw holding it on the other ones missing. I ac motor is new. i have so much money in it its not even funny. only think that could happen is the trans and engine. would love to convert rear disk turbo,doh cam head,etc. no money and the parts are expensive,plus i've nevre messed with an engine or trans,turbo,to do the stuff. it has 193000 miles on it and still runs great when it wants to. Thanks for all the inputs so far guys. my enterior lights or fried the who harness,so at night i put leds on the dash to see my gauges. i know thew work enterior because i ran it to the radio lst month after they were fried taped a bunch of them up. dash probly needs to come out but that looks like a bitch. to put in.

Why are you throwing so much money in just parts into the car man. There are ways to test pretty much everything you have replaced. A TPS doesn't just need to be replaced at a certain interval, read the resistance on it and compare it to spec.

Just because you replaced all the vacuum lines does not mean that it can't still have a vacuum leak. My recent one came from the gasket between the upper and lower manifold. You can get leaks from everything from cruise control, to the throttle body mounting to where the intake manifold meets the head.

I dont know how to check plus i see changing parts a good thing in the long run,just my opinion. it still needs to be replaced.

how could you easilt trace aleak,instead of replacing all the gaskets and lines?

plus i dont know how to check for the voltages and what they should read. i searched and still cant figure out how .

should i let a mechanic look it over?its my only ride, plus i dont have the money.

its like it want to hesitate on a stop or take off in first.then its fine or when air is on its idled at 750-800 should i go up on it? It maybe my short ram messing it up or the mas sensor,code read 170 after every 25 miles and sometimes i can drice like 100 to 200 miles long distances and it wont do it or show mil code till i get back in the city and drive sppeds of 55. its almost like the faster i accelrate the better it runs. it has a weird feel whendriving sppeds of 45 or lower. ;like the fuel hesitates ,i guess hard to describe and explain. thanks for the input so far guys and sorry to bother you.

hey, i have a 7G, but the only time ive noticed what you are saying is when ive disconected the battery on my car, then the comp needs to relearn everything. but you could have a vacuum leak. 98 percent of the time, when i see cars come in for a problem like that, its a vacuum leak somwhere. vacuum leaks can cause major headachs lol. but as far as testing for the leaks, my shop has a SNAP-ON product that pumps smoke into the manifold and if you see somke, bingo, lol. but there are other ways to check too.

Thanks man. what are some other ways to check for vaccum leaks?

i tighten up all the exhaust bolts intake bolts and throttle body. I cheched mu vaccum lines again and just about everything else. I could see. Could it perhaps be the throttle body postion sensor is faulty or not in th correct position. What about the fpr,fuel pump or fuel injectors have never been replaced,the mass air flow sensor was used. I just put headers on it with my short ram intake could the excessive heat cause it to do that. I need to buy a lower timing cover on it and install my water pump but i dont want to mess with the timing belt. i just had it and the balnace shaft replaced by a tech last year.
I'm going crazy trying to find the problem and no luck so far. Aggrevated.

Do you have a digital volt meter?

yes

Ok, to check a TPS set your DVOM to the Ohms setting, if its auto ranging then leave it alone from there if not then set it at 200 Ohms to start. With the throttle closed check the resistance across signal (should be a white wire) and ground (black).

Let me know what the reading is.

Ok I will do it first thing tomorrow.

I checked for all vaccum I made some stuff and sprayed on all vaccum lines exhaust intake,cruise control vaccum throttle body,and fuel injectors while running the engine and listened for it to idle up(change idle spped) and no luck. I think I'm pretty sure I have no vaccum leakes. I reset the battery and I ran it for about 30 miles,no code 170 yet. I put new header on because my stock had a hole in it. could that have been the culprit. Its idleing around 750-800.

my car idles right around there with out the A/C on (give or take a few rpm lol) but thats pretty close. when the A/C clutch Kicks on, the rpm drops for a sec, then the ECU compensates for the A/C being on and raise's the idle. but that happens real quickly and is usually a smooth transistion on or off. if you want to check the tps do what 6G72 said and report back to us and im sure one of us can compare with you. or check the specs.

I saw a black wire,yellow with a red stripe.and two green wires,one with a white stripe and I did'nt get no reading just 0 on my auto ranging dvom. The car was not running and the throttle plate was closed. I tried all of them with the black ground and no luck.

I dont know what the fuck im doing man. Being honest. I wish i could just pay one of you guys to complete my car for me,lol.

Seems to be running better. Now just to install my new struts.

what was the problem? ive been having a weird problem mine jumps up and down while rolling and im begining to think its my crank sensor since i keep getting a oil preasure light

Exhaust leak in manifold.

hmm mine leaks right at the dump from the manifold to the down pipe im going to get a new gasket tomorrow then

Let me know what happens