Car Pulses during accel and cruising?

Max777 · 04-22-2010, 12:19 PM

Yeah, so here I am yet AGAIN.

I have figured out EVERYTHING except fo this stupid problem on my car.

When I drive on the highway, i get this constant thub thub thub thub type of sound... however, it seems to be constant, and even happens at a simmilar rate when I'm accelerating from a stop as well, cruising at 3000 rpm in 4th, etc...

So far I've done this:

AFM
TPS
Driveshaft
New rear tires

That got rid of everything but this problem. It's not significant enough to where I cant drive the car, but it is annoying as all hell. I've tried to diagnose it to no avail... help please.

vex · 04-22-2010, 12:31 PM

Have you figured out if it's speed related or engine rpm related? That will go a long way to helping diagnose the issue.

Max777 · 04-23-2010, 06:40 PM

Well, when I accelerate, the "pulsation" goes like this:

instead of the engine revving like "vrrrrrrrrrrroooooooooooooooom"

it goes "vrooorooorooorooorooorooovoooooooovooooooovoooooo m"

Almost like it's rpm dependent, yet gets more "infrequent" as the revs increase?

And then I get this on the highway: "vroooom vroooom vvroooom vrooooom"

Rotary#10 · 04-24-2010, 01:16 AM

maybe you could record on video with a friend to show us whats happening.

***TitaniumTT*** · 04-24-2010, 07:23 AM

ECU and timing map
What are L readings while it's happening
how old are the plugs and wires and what are you using for ignition

MazdaMike · 04-24-2010, 07:43 PM

Did you properly adjust the TPS..you know jumping the initial set coupler and blah blah blah. Are you 100% sure you have no vacuum leaks? They can seal and open in relation to engine temperature. I would check between the extension manifold and the LIM...its common that people remove the upper intake assembly from there and its possible that constant improper removal process has warped the manifold or made the gasket fail.

junito1 · 04-26-2010, 05:35 PM

My car seems to accelerate in a pulsing manner also. A common driver would not be able to pick up on it. I think the OP made it sound a little too exaggerated.
I feel mine under light throttle/load acceleration. Anything near 0 vacuum is not noticeable.

I suspect one of my injectors being leaky or maybe the fact that there is 6psi diff in compression ratio between f/r rotors.?

MAybe the fact that i have full s4 TII efi running a s5 block. (heard spark plug holes area bit diff from s4/s5blocks)

MAybe its normal for a rotary?

Max777 · 05-03-2010, 11:27 AM

Plugs JUST got changed, plug wires all show simmilar resistance. They were around 5K ohms and 8k ohms last time I checked. I set the coupler, adjusted the TPS to 1K ohm at idle, and set the idle to as close to 750 as I could.

I checked the timing, and it's dead even on the leading side, but the trailing side #1 plug shows the timing a little off when it's hooked up.

04-22-2010, 12:31 PM	#2
vex RCC Loves Me Not You Join Date: Jul 2008 Location: Influx. iTrader: (6) Posts: 2,113 Rep Power: 19	Have you figured out if it's speed related or engine rpm related? That will go a long way to helping diagnose the issue. __________________ The Official FC Radiator Thread My Project Thread: Cerberus CCVT Virginia Rotary Group

04-23-2010, 06:40 PM	#3
Max777 Pirate Join Date: Mar 2008 Location: Central IL iTrader: (5) Posts: 1,323 Rep Power: 18	Well, when I accelerate, the "pulsation" goes like this: instead of the engine revving like "vrrrrrrrrrrroooooooooooooooom" it goes "vrooorooorooorooorooorooovoooooooovooooooovoooooo m" Almost like it's rpm dependent, yet gets more "infrequent" as the revs increase? And then I get this on the highway: "vroooom vroooom vvroooom vrooooom" __________________ Rotaries:They are NOT that complicated!

04-24-2010, 01:16 AM	#4
Rotary#10 Rotorhead Join Date: Sep 2008 Location: "the town " Oakland iTrader: (1) Posts: 219 Rep Power: 17	maybe you could record on video with a friend to show us whats happening. __________________ Currently running: 90 GTUs converted to S5 TurboII. Track car. 90 N/A GTUs.. Running project car 89 N/A GTUs in Black #2 10/6/18 Blown coolant seal undergoing rebuild and restomod.

04-24-2010, 07:23 AM	#5
*TitaniumTT* Test Whore - Admin Join Date: Mar 2008 Location: Right Behind you son iTrader: (4) Posts: 4,581 Rep Power: 10	ECU and timing map What are L readings while it's happening how old are the plugs and wires and what are you using for ignition __________________ -The Angry Stig- DGRR 2009, 2011, 2012 & 2013 - Best FC DEALS GAP!! WOOHOOOO!!!!! 2015 Audi S4 - Samantha - Zero Brap S4 2004 RX8 - Jocelyn - 196rwhp, 19mpg fuel to noise converter 2000 Jeep Cherokee Sport - Wifey mobile - Now with 2.5" OME lift and 30" BFG AT KO's! So it begins 1998 Jeep Cherokee - 5 spd, 4" lift, 33" BFG's - Rotary Tow Vehicle 1988 'Vert - In progress 1988 FC Coupe - Gretchen -The attention whore BEAST! I'm a sick individual, what's wrong with you? I'm pure Evil I'm still insane, in the best possible way. I think Brian's idea of romance is using lube. Your rage caused the meteor strike in Russia. The Antichrist would be proud of his minion. You win with your thread. Most everything It's a truck with a steel gate on the back. Just a statement of fact Motec M820, AIM dash, ported 13B-RE Cosmo, 6-spd trans, 4.3 Torsen, custom twin wg fully divided mani, Custom 4" split into 2x 3" exhaust, Custom HMIC, Custom custom custom custom I like to welder stuff.... No Bolt-ons allowed. Dyno'ed @ Speed1 Tuned by me - 405rwhp on WG.... WM50 cuming soon. *-Angry Motherfcker Mode ENGAGED-**

04-24-2010, 07:43 PM	#6
MazdaMike S4 Owner Join Date: Jun 2008 Location: Tottenham, ON, Canada iTrader: (0) Posts: 48 Rep Power: 0	Did you properly adjust the TPS..you know jumping the initial set coupler and blah blah blah. Are you 100% sure you have no vacuum leaks? They can seal and open in relation to engine temperature. I would check between the extension manifold and the LIM...its common that people remove the upper intake assembly from there and its possible that constant improper removal process has warped the manifold or made the gasket fail. __________________ 1985 Mazda RX7 GSL 13B, Holley etc 1997 Mazda MX6 LS - DD lowered on 17s

04-22-2010, 12:19 PM	#1
Max777 Pirate Join Date: Mar 2008 Location: Central IL iTrader: (5) Posts: 1,323 Rep Power: 18	Car Pulses during accel and cruising? Yeah, so here I am yet AGAIN. I have figured out EVERYTHING except fo this stupid problem on my car. When I drive on the highway, i get this constant thub thub thub thub type of sound... however, it seems to be constant, and even happens at a simmilar rate when I'm accelerating from a stop as well, cruising at 3000 rpm in 4th, etc... So far I've done this: AFM TPS Driveshaft New rear tires That got rid of everything but this problem. It's not significant enough to where I cant drive the car, but it is annoying as all hell. I've tried to diagnose it to no avail... help please. __________________ Rotaries:They are NOT that complicated! Last edited by Max777; 04-22-2010 at 12:20 PM.. Reason: better info

04-26-2010, 05:35 PM	#7
junito1 The Newbie Join Date: Mar 2010 iTrader: (0) Posts: 12 Rep Power: 0	My car seems to accelerate in a pulsing manner also. A common driver would not be able to pick up on it. I think the OP made it sound a little too exaggerated. I feel mine under light throttle/load acceleration. Anything near 0 vacuum is not noticeable. I suspect one of my injectors being leaky or maybe the fact that there is 6psi diff in compression ratio between f/r rotors.? MAybe the fact that i have full s4 TII efi running a s5 block. (heard spark plug holes area bit diff from s4/s5blocks) MAybe its normal for a rotary?

05-03-2010, 11:27 AM	#8
Max777 Pirate Join Date: Mar 2008 Location: Central IL iTrader: (5) Posts: 1,323 Rep Power: 18	Plugs JUST got changed, plug wires all show simmilar resistance. They were around 5K ohms and 8k ohms last time I checked. I set the coupler, adjusted the TPS to 1K ohm at idle, and set the idle to as close to 750 as I could. I checked the timing, and it's dead even on the leading side, but the trailing side #1 plug shows the timing a little off when it's hooked up. __________________ Rotaries:They are NOT that complicated!