Let's talk about tip in throttle responce.
Thread Starter
Drifting
Joined: Dec 2000
Posts: 1,785
Likes: 91
From: Leander TX
Let's talk about tip in throttle responce.
I am still having a problem with my tip in throttle responce. The car basically falls flat on it's face like it wants to stall out every time I give it WOT on a rolling start. It is not as bad while stopped then going to WOT but it is still present. After the enitial almost stall for a second the car takes off like a bat out of hell with no other problems. Here is what I have done to correct this problem with no fix
*new manifold gasket
*new runner and throttle body gaskets
*rebuilt and flow matched injectors With all new seals
*new cap, rotor, plugs, and wires
*MSD ignition coil (HEI under cap unit)
*fuel filter has less than 2K miles as well as the fuel pump
*checked all sensors (MAD sensor testor kit) all within specs
*heated O2
*Hyperech chip
*cleanned K&N filter
Other mods on car that I haven't thought about in this problem
*cut lid
*gutted cat
*smog elimination
*MAF gutted and ported (MAD unit)
*Air foil
*flowmaster catback
Am I missing something? Could my car just be starving for fuel for that second? If so, I have an AFPR but I have never touched the setting that the previous owner set it at as I didn't have any performance problem till a couple years after purchase. Can you please help out. Any insight would be appreciated.
*new manifold gasket
*new runner and throttle body gaskets
*rebuilt and flow matched injectors With all new seals
*new cap, rotor, plugs, and wires
*MSD ignition coil (HEI under cap unit)
*fuel filter has less than 2K miles as well as the fuel pump
*checked all sensors (MAD sensor testor kit) all within specs
*heated O2
*Hyperech chip
*cleanned K&N filter
Other mods on car that I haven't thought about in this problem
*cut lid
*gutted cat
*smog elimination
*MAF gutted and ported (MAD unit)
*Air foil
*flowmaster catback
Am I missing something? Could my car just be starving for fuel for that second? If so, I have an AFPR but I have never touched the setting that the previous owner set it at as I didn't have any performance problem till a couple years after purchase. Can you please help out. Any insight would be appreciated.
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: Let's talk about tip in throttle responce. (85WHITEZ51)
Try increasing the TPS base idle voltage. You can go to 0.;67Vdc before the ECM throws a code; I run mine around 0.65Vdc.
Then advance base timing to just under the point where knock counts cause the ECM to pull timing at WOT and high RPM. You will need a scan tool for this one. It that's a HyperTech Stage II chip, you may not be able to give it much beyond +6deg.
Try the cut lid, it won't hurt and will work well with that K&N.
Then advance base timing to just under the point where knock counts cause the ECM to pull timing at WOT and high RPM. You will need a scan tool for this one. It that's a HyperTech Stage II chip, you may not be able to give it much beyond +6deg.
Try the cut lid, it won't hurt and will work well with that K&N.
Former Vendor
Joined: Jun 2001
Posts: 7,204
Likes: 6
From: St Marys PA
Re: Let's talk about tip in throttle responce. (65Z01)
The problem is, what ever mods you have done, probably more air flow. Caused the stock *pump shot* to not be enough. Very common with these cars. The pump shot has the same effect that a carb has when you move the throttle. It give that extra squirt of gas to accomidate the added airflow until the ecm can adjust for it.
My car, stock, after messing with the air box, MAF, exhaust got really bad too. I simply added more AE accelerated enrichment *pump shot* and the problem disappeared.
That what I think the problem is. There is probably a bit of knock associated with it too since the engine is going lean.
Later :cheers:
My car, stock, after messing with the air box, MAF, exhaust got really bad too. I simply added more AE accelerated enrichment *pump shot* and the problem disappeared.
That what I think the problem is. There is probably a bit of knock associated with it too since the engine is going lean.
Later :cheers:
Le Mans Master
Joined: Aug 2000
Posts: 5,192
Likes: 1
From: Airport Cruise-in 1 Veteran Airport Cruise-in 2 Veteran
Cruise-In II Veteran
Re: Let's talk about tip in throttle responce. (85WHITEZ51)
Could my car just be starving for fuel for that second? If so, I have an AFPR but I have never touched the setting that the previous owner set it at as I didn't have any performance problem till a couple years after purchase.
Melting Slicks
Joined: Jun 2001
Posts: 2,525
Likes: 1
From: Sarasota, FL
Re: Let's talk about tip in throttle responce. (War Machine)
I'm with Ski, your mods may have increased airflow so that the "pump shot" which is an uncalculated squirt of gas may not be enough for the air your engine is pumping. Also I would suggest running with a fuel pressure gauge attached and see if there is a momentary drop in FP as you floor the accelerator. Good Luck.
Bob
Bob
Safety Car
Joined: Mar 2000
Posts: 3,620
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From: Hillsboro OR
Re: Let's talk about tip in throttle responce. (BobMachus)
I also agree with ski and bob. Make sure the TPS is woking okay too. If its giving flaky readings, the ecm will not put in the correct pump shot.
Drifting
Joined: May 2001
Posts: 1,295
Likes: 2
From: Surprise Arizona
Re: Let's talk about tip in throttle responce. (85WHITEZ51)
I had a similar problem. At idle if I snapped the trottle open It would have a noticible lag, then the RPM would come up. Basically when the throttle opened the engine would lag a bit then go like he!!. Turned out to be the ECM was not recognixing the input from the TPS. Took it to a guy with a scan tool. He found the problem. Replaced the ECM and all was better.
Thread Starter
Drifting
Joined: Dec 2000
Posts: 1,785
Likes: 91
From: Leander TX
Re: Let's talk about tip in throttle responce. (Paul G)
Thanks for the ideas so far. I think I worded some of my previous post wrong as it should state that everything I mentioned had been done to my car. The Other mods category has been done allready (smog elim.,gutted cat, etc.)
I have never looked at the AFPR as I don't have a gauge and it was working fine untill about a year ago.
A few of you mentioned that the "pump shot" may not be enough. How would I go about adding more fuel? I think that would probally be my problem. I have just put a brand new fuel pump in so that couldn't be the problem. Do I just need to increase the fuel pressure. I really have no idea as what the pump shot is or how to increase it so please infom me.
You also mention the ECM, are you saying that it could be bad or is it just that since the 85 ECM's don't work nearly as fast that that is my problem.
Thanks again.
I have never looked at the AFPR as I don't have a gauge and it was working fine untill about a year ago.
A few of you mentioned that the "pump shot" may not be enough. How would I go about adding more fuel? I think that would probally be my problem. I have just put a brand new fuel pump in so that couldn't be the problem. Do I just need to increase the fuel pressure. I really have no idea as what the pump shot is or how to increase it so please infom me.
You also mention the ECM, are you saying that it could be bad or is it just that since the 85 ECM's don't work nearly as fast that that is my problem.
Thanks again.
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Thread Starter
Drifting
Joined: Dec 2000
Posts: 1,785
Likes: 91
From: Leander TX
Re: Let's talk about tip in throttle responce. (85WHITEZ51)
Forgot to mention that the TPS sensor is working fine. I have it set at .54 at idle and it gets to about 4.5 at WOT. Should I adjust it? I thought it was supose to be at .54 at idle. I have been known to be wrong though. :D
Drifting
Joined: May 2001
Posts: 1,295
Likes: 2
From: Surprise Arizona
Re: Let's talk about tip in throttle responce. (85WHITEZ51)
Your TPS is set right on the money. No need to adjust it.
My problem was the ECM itself went bad and did not know that the throttle was opened because the TPS value was not being seen by the ECM. The only way to check for this is with a scan tool or diacom etc.
I dont know about the pump shot these guys are refering to. Never heard of that before??? Carburators have an accelerator pump that shot extra fuel down the hole when the throttle opened. Never heard of anything like that with fuel injection.
My problem was the ECM itself went bad and did not know that the throttle was opened because the TPS value was not being seen by the ECM. The only way to check for this is with a scan tool or diacom etc.
I dont know about the pump shot these guys are refering to. Never heard of that before??? Carburators have an accelerator pump that shot extra fuel down the hole when the throttle opened. Never heard of anything like that with fuel injection.
Thread Starter
Drifting
Joined: Dec 2000
Posts: 1,785
Likes: 91
From: Leander TX
Re: Let's talk about tip in throttle responce. (Paul G)
If it is the ecm, how hard would it be to up-grade to a better unit like the ones used in 86+ years. I think they are like 50 times faster than the 85. Would all I need to do the conversion be a 86+ecm and corisponding chip? Is it even possible to do? Hate to spen $100 on an ecm that still going to be far poorer than a newer unit.
Race Director
Joined: Aug 2000
Posts: 14,130
Likes: 7
Cruise-In II Veteran
Re: Let's talk about tip in throttle responce. (Paul G)
I had a similar problem in my F body and it turned out to be that crappy hypertech chip.I put the stock chip back in and drove it around a couple hours to relearn itself and the tip in problem was gone.Ill never use those chips again.
I also learned later my new GM chip made the car run better then the ADS chip the previous owner had installed.(GM upgraded their chips over the years so driveability is much better then back in the 80's)
Just an idea.Every car seems different while being closely the same.
:)
Thread Starter
Drifting
Joined: Dec 2000
Posts: 1,785
Likes: 91
From: Leander TX
Re: Let's talk about tip in throttle responce. (Bill's86Coupe)
Do you know where I could get a factory 85 auto chip? I have very little $$$ and I only have the hypertech chip along with two ADS super chips. Car came this way.
Former Vendor
Joined: Jun 2001
Posts: 7,204
Likes: 6
From: St Marys PA
Re: Let's talk about tip in throttle responce. (Bill's86Coupe)
All items are pointing to the pump shot. It doesn't take much to screw it up.
It may even be a more prominate problem with the slower ecm.
I agree with the other too. Make sure the ecm is seeing the TPS first. Then either find someone to tune your car or start yourself. Its the only way to get it close to 100%.
Good luck. :cheers:
It may even be a more prominate problem with the slower ecm.
I agree with the other too. Make sure the ecm is seeing the TPS first. Then either find someone to tune your car or start yourself. Its the only way to get it close to 100%.
Good luck. :cheers:
Race Director
Joined: Aug 2000
Posts: 14,130
Likes: 7
Cruise-In II Veteran
Re: Let's talk about tip in throttle responce. (85WHITEZ51)
As far as I know,you can still get them from GM.I paid about 40-50(cant recall exact) bucks for a new 86 chip and my car ran fantastic with it,idle better and so forth.
The chip is automatically upgraded by GM to cover some problems they had with the old ones.
However,pls do the above suggestions before throwing money away on a chip.
It worked for me but may not work for you.
However,if you need a chip burned again,why not talk to craig marcho here?
I heard nothing but praise from his 85 proms he makes.
:)
The chip is automatically upgraded by GM to cover some problems they had with the old ones.
However,pls do the above suggestions before throwing money away on a chip.
It worked for me but may not work for you.
However,if you need a chip burned again,why not talk to craig marcho here?
I heard nothing but praise from his 85 proms he makes.
:)