acelleration problem?
 

HI all,got a low miles 90 zr-1 that i thought i had a fuel problem with,but after checking or replacing both pumps pulling and cleaning tank,new o2 sensors and checking everything else other owners have suggested. in nuetral the engine wont run over 3000 rpm .im told this is normal,because of the rev limiter, but this car wont accelerate past 3000rpm in gear, making it near impossible to drive!i would sure appreaciate any input from anyone.thanks, Harold

Re: acelleration problem?
 

Does your SES light up when you cycle the key to run?

Re: acelleration problem?
 

Harold:

Sounds like secondary fuel injectors aren't firing. Could be a bad relay or bad injectors. Are the injectors the originals?

Re: acelleration problem?
 

jueffvette, this car is spooky!ses lite comes on with key, but most times it goes outwhen engine starts right now i got in the car and engine zinged right past 3000rpm in neutral. but ill bet if i take it out to drive, it wont go past 3000rpm. code scanner shows code 61, but i think we have covered most everything such as both fuel pumps both o2sensors, checker vaacum pump,pulled and cleaned gas tank. this is a 10k mile car,that has been in storage.any help will be appreaciated! if you have the time,call me at 800-475-5431 days 6am-2pm thanks a bunch!Harold

Re: acelleration problem?
 

did you do a vaccume ck on the line that goes under the plenumfrom the vaccume pump? you proably have Vaccume issue under the plenum. usaual culprits accuators vaccume canister or the port throttle selinoid has died.

Re: acelleration problem?
 

Just wanted to make sure that the SES light did function. Would not be the first time the bulb had been removed.

Code 61 is a secondary vacuum fault. You more than likely have a bad check valve or your storage canister could be faulty. Need to run through the diagnostic checks in the service manual.

Re: acelleration problem?
 

Some of the other culprits in a DTC 61 are bad actuators, 2* solenoid, leak anywhere in the vacuum hose spyder for the 2* system, and a bad ECM.

If the code 61 sets the motor will be limited to 3k rpm. It's like driving a toyota!

I had this on my 90 about a month ago....turned out I pulled the plenum for nothing as it was the ECM. If you have a spare swap it out & see what happens. It might save you a plenum pull.

:cheers:
Tom

Re: acelleration problem?
 

Really? Mine sets a 61 all the time, but I have no problem hitting redline.

My secondaries are tied open until I figure out how to put rotary actuators on it.

Re: acelleration problem?
 

Rotary actuators?? Im not following you..

Re: acelleration problem?
 

According to my 90 FSM's diagnostic write up for DTC 61 the rpms are limited to 3k and the secondaries are cancelled.... it's what my car was doing...maybe because it was my ECM and not anything in the 2* system that was the cause of DTC 61 that my rpm's were limited to 3K????

I often thought that little servo motors in place of all the vacuum stuff would work but I'm not that talented....too bad we don't have fly by wire throttle controls because I would think it would be an easy adaptation from there.:icon_scra :o

Re: acelleration problem?
 

hi all, harold again, we checked all systems as to the tips you all sent in, such as secondary port vacuum system, and it holds 12hg. going under the plenum and also back to the pump.fuel pumps are new as are o2 sensors.car still shows a code 61, and wont run over 3000 rpm.if engine passes the vacuum pump test ,can i assume everything is ok under the plenum,or do i need to take the plenum off and check furthur?also, is there a way to check the ecu. i really appreaciate your input. thanks again Harold

Re: acelleration problem?
 

if its holding vaccume i believe you should be ok under there ,i think the onlt exception would would be the port throttle selinoid? but would have to defer to jeff on that to know for sure . have you tried disconnedting the battery for a couple of minutes then rahooking it uop to reset any codes you may have. wish i could help more . oh havve you cked to see if you vaccume pump comes when you turn the key to on ? .

Re: acelleration problem?
 

So you have a tech 1?

Re: acelleration problem?
 

to jeffvette, what thew heck is a tech 1? harold

Re: acelleration problem?
 

Tech 1 is the tool you need to troubleshoot the system.

Re: acelleration problem?
 

Like this:

http://www.rotomation.com/a032.htm

Should be fairly simple to tie into the existing circuit for the solinoid to run this thing. I've only done wayyy preliminary thinking about it though.

KT

Re: acelleration problem?
 

I may be wrong but a vac test on the line going to the 2* system from outside (vac pump) will only test the check valve and the tank(?), and that the control solenoid is not leaking vacuum. The actuators maybe (I stress maybe ) tested using the vac line to the MAP under the ECM as it T-ee's off of the vac feed from the solenoid to the actuators.....I THINK????

Not having a Tech1A was why I was mad when I finally concluded that my ECM was the root of my code 61....without it and it's testing software I couldn't do all the diagnostics...I had to make assumptions and follow either a "yes" or "no" answer to the end of the diagnostic tree to find I had "guessed" wrong. Had I just swapped out the ECM before I pulled the plenum I would have seen that the ECM was at fault from the get go.:redface:

:cheers:
Tom
If I had a spare ECM I would lend it to ya to test...but it's now in my car!:o

Re: acelleration problem?
 

hi all,Harold again,still suffering from same problem, wont rev over 3000rpm and ses lite still on. we cleared the ecm, and ses lite went out and engine would rev freely above 3000 and beyond. this lasted about a minute,and the ses lite came back on and engine wont rev past 3000 again.any ideas?thanks,harold

Re: acelleration problem?
 

It keeps coming back because you have not corrected the issue of lack of vacuum.

Re: acelleration problem?
 

hi guys, can anyone tell me where i can buy a tech 1 tool? thanks, Harold

Re: acelleration problem?
 

hi all, Harold again, we pulled the plenum off to check for vacuum leaks and found none, dont have a tech 1 tool ,so im kind of lost. is there a way to check the vacuum solenoid or am i looking in the wrong place?to refresh your memory, i have a code 61, and have replaced both fuel pumps and socks and both o2 sensors ,checked all vacuum lines outside and under the plenum. nothing has helped. HELP!!! HAROLD

Re: acelleration problem?
 

You can stumble through without a tech 1, but you will need a scan tool... and I'm not talking about just a code reader. You need to see sensor outputs.

The results of the dig tree are either faulty connection/faulty ecm/faulty solenoid/faulty actuator or hose.

Re: acelleration problem?
 

just an Idea did you ck each of the actuators to see if they are opening the secondary throttle blades and individually holding vaccume?

Re: acelleration problem?
 

Harold,

I just went thru this DTC 61 on my 90. I didn't have the correct software for my scan tool which meant that I could not do the "Feild Tests" required by the diagnostic flow chart in the FSM.

It comes down to the situation that you are reasonable sure that the vacuum connections and all the vacuum equipment works, holds vacuum? If yes then the fault or source of the 61 is electrical. Therefore the only three possible electrical items are:

2* control solenoid, can hold vacuum but not open on command from ECM. Coil part is fried or something?

ECM, I think all it does is ground the solenoid??? so it opens.

MAP sensor t-ed off of the left actuator. That MAP is under the ECM brkt. This is not included in the flow chart so I doubt it has an effect on 61. I think in theory this MAP is the only way the ECM gets to "see" what the vacuum in the 2* system is because I think the solenoid is only a two wire connection. Therefore there is no reference signal back to ECM.

Wiring. Outside shot is wiring preventing any communication among the solenoid & ECM. I would think you could see damaged wire but who knows.

What I did because of lack of the proper software was to r&r the 2* solenoid and reassemble. DTC 61 re-set, so I knew it was the ECM in my case as I could not find anything else while I was under the plenum using a test light and my Mark1 eyeball.:redface:

Do you have a spare good 2* solenoid? ECM? I have spare solenoids, but used my last ECM on my repair.

E-bay sometimes has Tech1 & Tech1A's listed but the trick is to get the right software. They have a web site, Vertronix.

:cheers:
Tom

Re: acelleration problem?
 

hi all, i believe we have ruled out everything but the ecm. who has the best deal on replacement ecm,thank, Harold

Re: acelleration problem?
 

For a remaned unit (with a warranty) check with your local Chevy dealer.
I bought one last year for $134 plus overnight shipping charges.
I've got the part number here somwhere.....

Re: acelleration problem?
 

GM part #: 16196394

Re: acelleration problem?
 

Kurt's got a few NOS still on the shelf if you're a NCRS kind of guy, but be prepared to spend an arm and a leg and you'll probably have to toss in your first born as well to seal the deal.

Re: acelleration problem?
 

Who is Kurt, and how bad is he going to hurt me?Harold

Re: acelleration problem?
 

Kurt White of White Racing Products.
http://www.whiteracingproducts.com/home

He is "Miura Parts" on eBay.

Figure on spending $450 or so.

Re: acelleration problem?
 

hI ALL, WANT TO THANK ALL YOU GUYS FOR YOUR TIPS, IT TURNED OUT TO BE THE ECU. NOW THE CAR RUNS GREAT! ONE OTHER PROBLEM, ANY IDEAS ON TURNING OFF THE SERVICERIDE CONTROL? THANKS AGAIN, HAROLD

Re: acelleration problem?
 

Harold:

ServiceRideControl will come on if you start the car three times without moving it. Drive it down the block, then turn it off and restart it.
The light should then reset and go out.
If it stays on, you could be having problems with the FX3 shock actuator.
Here's a link to a site where you can buy replacement gears for the FX3.
http://captainzcnc.com/index.html


Where did you get the ECM and how much did it cost?

Tom

Re: acelleration problem?
 

to tom c, a local auto parts store sent mine out to a rebuilder and cost 238.00. works fine! Harold