ChrisChung125

iTrader: (3)

Hey guys.

My car was sitting for ~2 years while I had the body repainted and repaired from the decade+ of MD salt damage. It took me a long time to get her back together. The garage it was in was relatively dust free, and I put FME where I could to keep exposed and open pipes clean. There were a number of small problems when I went to start her up for the first time that I can get into if you think it's relevant, but it's a long list so I don't wanna start off with it.

Here's the problem so far:

I started my car up, drove it for about 45 minutes, parked, and started noticing that the idle was bouncing a little bit. The idle was a little high at about 850rpm, and would jump to 1000rpm and drop. It was almost as if it were hunting. (Not sure what the exact automotive term would be, but I've worked with generators and governors for a while, and that's what it seemed like to me.)

Next time I started her up, the bouncing was still there, and after about a 25 minute drive, started becoming more severe. It was only a problem when the car wasn't in gear. I noticed that by the end of the 25 minute drive, that the bouncing was a little more severe.

On the return leg of that same 25 minute drive, the bouncing got worse, and actually started happening while in gear. At this point, while not in gear, the idle was bouncing between 950 and 1150. In gear, it would bounce between 900 and 1050. Part way home, it actually started surging. To the point where it was unsafe. I would hold the throttle and I could see the boost come up to ~6psi, then it would drop off. It was actually much more severe in lower gears, so placing a load on the motor seemed to damp it a little bit.

After a bit of searching the forums, I found Damian's post:
https://www.rx7club.com/3rd-gen-archives-73/fixed-my-idle-problems-backfiring-bucking-more-242321/

I checked the TPS and everything was in spec. Some values a little far from ideal, but well within tolerances.

That's when I noticed that something was a little off.

I'm not sure exactly what that piece is called, but I'm pretty sure that those arms serve as the adjustable hard stops of the butterfly valves in the throttle body. I'm not sure if they're attached to the TPS or not, but the shaft looks like it goes all the way through. Anyhow, the issue is that they were sitting off of the stop by about 2-3mm. When I pushed it back down against the hard stop, there wasn't much resistance.

When I started the car back up, it idled perfectly - all surging and hunting gone.

I took the car out for about 45 minutes, nothing crazy. Didn't drive it particularly hard. Towards the end of the 45 minutes, it started again. Once I found a safe place to stop, I noticed that it was sitting off of the stop again. I tried to push it back, but found a bit more resistance than before. Pushed it back, everything was fine.

My questions:

What could be causing it to shift? It moves freely, with 0 binding while shut down.
What could have caused this? It NEVER did this before.

Thanks in advance.

DaleClark

iTrader: (55)

Might just be the throttle body binding up. Pull and clean the linkage and lubricate everything well.

Dale

ChrisChung125

iTrader: (3)

I'll give a try today or Sunday. It doesn't feel like binding, but that seems as likely as anything else.

Anyone know where I can find a component diagram of the throttle body, linkages, and tps?

RENESISFD

iTrader: (13)

^Probably the FSM, that's where I would look first.

arghx

iTrader: (3)

Does the engine have any mods or emissions removal?

Double_J

iTrader: (28)

What ECU?

ChrisChung125

iTrader: (3)

Mods:
Apexi intakes
Rx7store V-Mount
High Flow Cat
Apexi N1 Dual exhaust
Coolingmist water injection
Stock ECU with PF purple computer
AC and Air pump delete

ChrisChung125

iTrader: (3)

Factory Service Manual (FSM)?

scotty305

iTrader: (2)

Along with lots of other info, a link to the FSM can be found in the 3rd gen FAQ which is located here: https://www.rx7club.com/3rd-generation-specific-1993-2002-16/faq-3rd-gen-other-useful-links-68640/



Factory Service Manuals (FSM):
https://www.rx7club.com/3rd-generation-specific-1993-2002-16/94-fsms-available-download-449950/
https://www.rx7club.com/3rd-generation-specific-1993-2002-16/3rd-generation-fsm-more-984742/
Mobile-friendly:
https://www.rx7club.com/3rd-generation-specific-1993-2002-16/factory-service-manual-downloads-mobile-friendly-979872/

ChrisChung125

iTrader: (3)

Here's an update guys.

I tried to recreate the problem so that I could look a little more closely and what is physically binding the shaft. Well, the problem is gone... Well, at least it isn't a problem right now. I'm sure it'll come back.

I figure at the very least, I will go ahead and lubricate the entire linkage.

Anyone know what I should use to lubricate the throttle body? Is it okay to spary some WD-40 on the throttle valve shafts?

ChrisChung125

iTrader: (3)

For anyone that has this problem in the future, and the 7's been sitting for an extended period of time, spray a tiny bit of WD-40 on all linkages on the front and back of the throttle body, and cycle the throttle linkages with the car off to allow the WD-40 to work into the grooves.

When you manually cycle the linkages without any lubricant using full throws of the linkages, they'll return to their normal position and seem like everything is fine, but if you're driving like a responsible person in the city, then you're not really doing full throws so things can get stuck.

After I did that and drove the car for a couple of hours, everything worked itself loose.

Kind of a stupid problem, but I figure someone else is bound to have something like this happen to them too, someday.

misterstyx69

iTrader: (142)

Although my Car is an FC,I put an FD upper on,with Throttle body.
I had to get another throttle body as the one that I had kept sticking Fiercely.
You are lucky it was only 900 or so Rpm..This thing would stick like Half way.and you had to smack it!
Now,my FC throttle bodies,all have lube on them now,and I sprayed and cleaned them inside and out.
I notice that the inside gets build-up and it can prevent the Butterfly from closing.Maybe that is what was wrong with yours.

ChrisChung125

iTrader: (3)

Where did you notice the build-up?

I'd love to take the throttlebody apart and inspect the internals, but I don't have my garage anymore. I'd hate to be working in a dimly lit apartment garage with no real tools.

I may have to if the problem returns, but it looks like the gremlins are bay for now.