RX7Club.com - Mazda RX7 Forum

RX7Club.com - Mazda RX7 Forum (https://www.rx7club.com/)
-   2nd Generation Specific (1986-1992) (https://www.rx7club.com/2nd-generation-specific-1986-1992-17/)
-   -   Car stalls when i hit the gas after it starts, bad afm or map sensor? (https://www.rx7club.com/2nd-generation-specific-1986-1992-17/car-stalls-when-i-hit-gas-after-starts-bad-afm-map-sensor-1038893/)

wthdidusay82 06-23-13 06:19 PM

So everytime i start my car i have a hard time getting it to stay running , it will hold an idle if i can get it to stay running but it has a hard time, when I hit the gas it after starting it , it acts as if I'm letting off the throttle rather than applying it and just stalls and doesn't rev up.

I can sometimes get it to start and hold idle if I can get it to rev around 2-3k rpms and hold it until it can maintain an idle on its own and then it will rev without dying and even hold an idle at whatever rpm I put it at though it will be loopy/surge (bad tips/bad adjustment on tips I assume)

I bought the afm off someone on here he said he never used it and bought it off someone else.

The map sensor on my car I assume is the correct one but its missing the sticker on the top to show the model it is.

Is there any way to test these to confirm if they're good or bad?

Could it just be an adjustment on my TB? I did disconnect the throttle cable.and it actually idled lower than it did with it attached so I figured that wasn't the problem.

I have all emissions removed, the TB is a.jdm model, engine is freshly rebuilt with no mileage under load on it 'yet'

Rotary > Pistons

wthdidusay82 06-23-13 08:46 PM

no one has any input, guess I know as much as y'all.

I'm gonna get another afm, boost sensor, and adjust my tps.

Rotary > Pistons

j9fd3s 06-23-13 08:52 PM

adjust the TPS first, and then if you can get it to hold an idle under 1000rpm, check the timing

wthdidusay82 06-23-13 09:01 PM

I've had it hold idle at 800 rpms with the throttle cable disconnected it was just loopy, that was when the car was hot not cold.

When its cold and I start it pushing the gas pedal makes it stall, after its warm it doesn't do.it anymore at least not that I can notice.

Im gonna get another boost sensor and afm , if they're not the problem I have backup parts.

I have an extra tps and sensor for the back of the waterpump as well.

There's nothing else it could be is there? my TB is jdm and to my understanding the secondary plates open even when the car isn't fully warmed up.

Rotary > Pistons

My5ABaby 06-23-13 10:16 PM

Will it idle if you unplug the BAC?

SonicRaT 06-24-13 12:23 AM

There seem to be a whole host of issues going on with this car, and the more random playing around and doing things seem to be making it worse. Here's what you should do:


1) Stop randomly replacing parts for no reason. Unless you follow the FSM method of inspecting a part and find it out of spec, there's no reason to be constantly swapping parts.
2) Compression check. If the engine sucks, it only compounds every other little problem along the way. I don't care if the thing ran fine last week or it was just rebuilt. This is an absolute first step in dealing with rotaries.
3) Check and make sure the engine ground is properly connected to the transmission bolt
4) Reconnect the BAC.
5) Fix the vacuum leaks around the EGR and fix that TID.
6) Reset the throttle body settings. This means make sure there is no tension on the throttle cable, close the throttle plates via the throttle stop screw and then turn it open 1/2 a turn.
7) Adjust the TPS to 1v only after the above has been done.
8) Start the car. You may need to hold it at a set speed, try to keep it low and allow the car to fully warm up. Once fully warm, use the throttle stop screw to set the idle at the lowest you can get it to be consistent. It will need to at least be under 1K rpm if you have any hope of verifying timing/tps settings.
9) Adjust timing if RPM is <1000
10) Readjust TPS once the RPM is around 850-900.

wthdidusay82 06-24-13 07:40 AM


Originally Posted by SonicRaT (Post 11503194)
There seem to be a whole host of issues going on with this car, and the more random playing around and doing things seem to be making it worse. Here's what you should do:

2) Compression check. If the engine sucks, it only compounds every other little problem along the way. I don't care if the thing ran fine last week or it was just rebuilt. This is an absolute first step in dealing with rotaries.
3) Check and make sure the engine ground is properly connected to the transmission bolt

I don't have a compression tester but I can say the engine was rebuilt with like new housings.

Where is this engine ground that is connected to the transmission bolt? I have a ground that goes
to the transmission sandwiched .between the engine and trans bellhousing, did I put the ground in the wrong place ?

I'm trying to.figure out where the ground on the firewall on the passenger side goes that's not connected. Iirc it connect to the lim/uim mating point, I may have to take a trip to.the junkyard and get the wiring for it.

I did reconnect the bac and it didn't seem like it did anything. hmm...could I have it connected to the water sensor and the water sensor connected to the bac connector? I really doubt it because the wiring will only reach the way its connected now.

I'm going to get a corksport tid when I get paid.

Rotary > Pistons

satch 06-24-13 09:25 AM

The BAC helps prevent the idle from dropping below 750 rpm especially when the engine is under load. It's likely not causing your current problems. If you had it always hooked up and the solenoid was stuck in the open position then it could cause the idle to be higher than it should.

texFCturboII 06-24-13 09:49 AM


Originally Posted by wthdidusay82 (Post 11503320)
I don't have a compression tester but I can say the engine was rebuilt with like new housings.

Where is this engine ground that is connected to the transmission bolt? I have a ground that goes
to the transmission sandwiched .between the engine and trans bellhousing, did I put the ground in the wrong place ?

There should be NOTHING between the mating surfaces of the engine and the bellhousing. That ground bolts to the back of the bell housing, IIRC. There should be a little notch out for it, even.


Originally Posted by wthdidusay82 (Post 11503320)
I'm trying to.figure out where the ground on the firewall on the passenger side goes that's not connected. Iirc it connect to the lim/uim mating point, I may have to take a trip to.the junkyard and get the wiring for it.

That little dangling guy also goes to the bellhousing.


Originally Posted by wthdidusay82 (Post 11503320)
I did reconnect the bac and it didn't seem like it did anything. hmm...could I have it connected to the water sensor and the water sensor connected to the bac connector? I really doubt it because the wiring will only reach the way its connected now.

This is entirely possible, but unlikely. If you ask me, I'd fix the vacuum leak you found on the TID (other thread) before you start taking anything else apart. The problem you are experiencing can very well be caused by un-metered air.


Originally Posted by wthdidusay82 (Post 11503320)
I'm going to get a corksport tid when I get paid.

Why not just get some PVC pipe and make a ghetto rig to be sure that a potential vac leak on the TID is the problem before throwing more money at things?

wthdidusay82 06-24-13 10:09 AM


Originally Posted by texFCturboII (Post 11503378)

There should be NOTHING between the mating surfaces of the engine and the bellhousing. That ground bolts to the back of the bell housing, IIRC. There should be a little notch out for it, even.

That little dangling guy also goes to the bellhousing.


the firewall ground I'm talking Bout is the metal tab coming off the firewall near the wiper motor

ill fix the ground near the starter and see if that helps.

as far as the PVC pipe, I'm not really sure how I'd do that, I figure the cork sport tid is an upgrade anyways

ill take some pics of the stuff in.question (mainly the wiring missing or connected wrong)
Rotary > Pistons

j9fd3s 06-24-13 11:02 AM

T2's can be picky, but it will never run right with a bad TID.

wthdidusay82 06-24-13 11:26 AM


Originally Posted by j9fd3s (Post 11503448)
T2's can be picky, but it will never run right with a bad TID.

that's why I'm gonna replace it with the cork sport one, I read it hard to connect to the stock airbox but ill figure it out

Rotary > Pistons

texFCturboII 06-24-13 02:00 PM


Originally Posted by wthdidusay82 (Post 11503392)
the firewall ground I'm talking Bout is the metal tab coming off the firewall near the wiper motor

ill fix the ground near the starter and see if that helps.

as far as the PVC pipe, I'm not really sure how I'd do that, I figure the cork sport tid is an upgrade anyways

ill take some pics of the stuff in.question (mainly the wiring missing or connected wrong)
Rotary > Pistons

It's pretty simple. You've got a 3" (?) outlet from the AFM and a 2"(?) inlet for the turbo.... so you need a 30* elbow of 2" PVC, a 2" coupler and a 3" to 2" reducing coupler, as well as 4 worm gear hose clamps. I'm sure you can figure it out from there, it will cost you $10, but it won't say corksport on it and it's a good test to see if it fixes your problem before you buy a $140 piece of metal. Or is it plastic? :icon_tup:

texFCturboII 06-24-13 02:02 PM

Wait, about the grounds: Are you referring to a single ground in post #7? Or two different ones? You've got the ground to the passenger shock tower, starter bolt, ECU ground to the block, and the dangler near the wiper motor accounted for, correct?

wthdidusay82 06-24-13 02:22 PM

I'd have to look for the one on the shock tower I remember seeing one near the headlights.

Rotary > Pistons

texFCturboII 06-24-13 02:23 PM

WHOOPS.... I meant driver side shock tower

wthdidusay82 06-24-13 02:27 PM

I'd have to check it might not be, do u have a pic? ill take a pic of mine

Rotary > Pistons

jjwalker 06-24-13 02:32 PM

I doubt it is the one on the driver side shock tower. It's for the ignitor coils and I don't think you can get spark without it grounded. I don't know of any reason to ever take it off either, as it all hidden underneath the secondary coils.

wthdidusay82 06-24-13 02:38 PM

2 Attachment(s)

Originally Posted by jjwalker (Post 11503654)
I doubt it is the one on the driver side shock tower. It's for the ignitor coils and I don't think you can get spark without it grounded. I don't know of any reason to ever take it off either, as it all hidden underneath the secondary coils.

yep that was bolted on, here's a pic of the tab not connected.

also something that I've heard the car doing is making a beep noise when I push the lock down, is that normal? also the lights on the doors don't start working immediately when I open the door, shouldn't they work without needing the key ?

Attachment 502363



Attachment 502364

Rotary > Pistons

texFCturboII 06-24-13 02:39 PM

I was just trying to ensure he had the ECU ground to the top of the block, really. Get your TID vac leak fixed, OP. Then troubleshoot from there.

wthdidusay82 06-24-13 02:56 PM

I have the one on the top of the block on driver side bolted on, no worries.

how fast does the Turbo even spin from idle?

Rotary > Pistons

Molotovman 06-24-13 05:19 PM

It sounds like you're getting a lot of unmetered air to me. Let the car idle and spray carb cleaner around the TID, recirc/blowoff valve(whatever you have), and intake manifolds.

wthdidusay82 06-24-13 05:54 PM

I did that already and the egr blockoff , tied, and lim/block seemed to have am.affect.

I'm hoping I can fix it by redoing the egr block off and replacing the tid

Rotary > Pistons

SonicRaT 06-24-13 06:22 PM

The EGR is so close to the LIM, that it might be the source all by itself. That's certainly a place to start. Once those things are done and you can get it to idle in the 900 neighborhood you can finally fix the timing/TPS.

wthdidusay82 06-24-13 06:27 PM

I just rtved the snot out.of the egr valve with ultra black rtv, now I have to wait for it to cure.

I also redid the seal on the air control valve near the firewall? I took it off and found out I had to put it back on but didn't use rtv assuming the gasket would seal, figured I'd put some rtv there as well.

Rotary > Pistons


All times are GMT -5. The time now is 04:24 PM.


© 2024 MH Sub I, LLC dba Internet Brands