4A-GE MK1 Engine 85 MKI Surging

nivlac · 04-22-2007, 01:08 AM

The other day I was driving and the car started jerking really bad. Every time I gave it gas t he rpms would drop and then jump up and drop again. The engine seemed fine under 2000 rpm and it idled fine. I thought it was the TPS so i disconnected it and tried driving. It seemed fine for a little while, then it started doing it again. It only seemed to happen while the engine was warm. The car has new plugs, cap, rotor, and wires. Any help would be greatly appreciated.

Mista 2 · 04-23-2007, 05:05 AM

my friend had this sort of problem with his car. it turned out to be the ecu

nivlac · 04-23-2007, 01:51 PM

Someone told me that it could be bad gas, so I put in a can of heat, and some octane booster. I haven't noticed any problems since. I'll get midgrade next time and hopefully I wont have a problem.

te51levin · 05-06-2007, 12:47 PM

It's always a good idea to re-burp the cooling system. Your TPS may be out of adjustment, too, so check that. I hope you don't mean to say that you drove around with the TPS disconnected; it should always be connected. The ECU depends on the signal it gets from the TPS.

One problem with many 4A-GEs is that the TPS connector is often broken, so you may have to wire or zip-tie the connector to the TPS so it does not fall off or wiggle loose, which could cause intermittent rough running.

nivlac · 05-07-2007, 01:04 AM

I don't have the problem anymore. I changed the fuel filter and bought better gas and its fine now.

halo07 · 10-24-2007, 03:53 AM

that is the exact same problem my car is having, i have replaced the same things and im still having trouble. could mine be the fuel filter or injectors too?

te51levin · 10-24-2007, 10:44 AM

It's much harder to diagnose things over the internet than it is on person. Without a lot more detail, it's gonna be nearly impossible to give you any useful information. Can you get someone local with MR2 experience to look at the car for you?

halo07 · 10-24-2007, 04:42 PM

i dont know anyone around dayton who has a mr2. i have seen like two mk1's in town but im always going the other direction and never get a chance to talk to them.

04-22-2007, 01:08 AM	#1 (permalink)
nivlac No Skills Join Date: Mar 2007 Location: Puyallup, WA Posts: 5 Thanks: 0 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	85 MKI Surging The other day I was driving and the car started jerking really bad. Every time I gave it gas t he rpms would drop and then jump up and drop again. The engine seemed fine under 2000 rpm and it idled fine. I thought it was the TPS so i disconnected it and tried driving. It seemed fine for a little while, then it started doing it again. It only seemed to happen while the engine was warm. The car has new plugs, cap, rotor, and wires. Any help would be greatly appreciated. Last edited by nivlac; 04-22-2007 at 01:10 AM.. Reason: grammar

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04-23-2007, 05:05 AM	#2 (permalink)
Mista 2 Cage Fighter Join Date: Nov 2006 Location: Adelaide, Australia Posts: 463 Thanks: 16 Thanked 21 Times in 21 Posts My Google Map iTrader Rating: (0/0% )	my friend had this sort of problem with his car. it turned out to be the ecu

04-23-2007, 01:51 PM	#3 (permalink)
nivlac No Skills Join Date: Mar 2007 Location: Puyallup, WA Posts: 5 Thanks: 0 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	Someone told me that it could be bad gas, so I put in a can of heat, and some octane booster. I haven't noticed any problems since. I'll get midgrade next time and hopefully I wont have a problem.

05-06-2007, 12:47 PM	#4 (permalink)
te51levin LithiaToyotaParts.com Join Date: Oct 2005 Location: Copperhead Road Posts: 3,699 Thanks: 50 Thanked 324 Times in 268 Posts My Google Map iTrader Rating: (193/100% )	It's always a good idea to re-burp the cooling system. Your TPS may be out of adjustment, too, so check that. I hope you don't mean to say that you drove around with the TPS disconnected; it should always be connected. The ECU depends on the signal it gets from the TPS. One problem with many 4A-GEs is that the TPS connector is often broken, so you may have to wire or zip-tie the connector to the TPS so it does not fall off or wiggle loose, which could cause intermittent rough running.

05-07-2007, 01:04 AM	#5 (permalink)
nivlac No Skills Join Date: Mar 2007 Location: Puyallup, WA Posts: 5 Thanks: 0 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	I don't have the problem anymore. I changed the fuel filter and bought better gas and its fine now.

10-24-2007, 03:53 AM	#6 (permalink)
halo07 Freakin sweet Join Date: Sep 2007 Location: Huber Heights Posts: 181 Thanks: 10 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	that is the exact same problem my car is having, i have replaced the same things and im still having trouble. could mine be the fuel filter or injectors too?

10-24-2007, 10:44 AM	#7 (permalink)
te51levin LithiaToyotaParts.com Join Date: Oct 2005 Location: Copperhead Road Posts: 3,699 Thanks: 50 Thanked 324 Times in 268 Posts My Google Map iTrader Rating: (193/100% )	It's much harder to diagnose things over the internet than it is on person. Without a lot more detail, it's gonna be nearly impossible to give you any useful information. Can you get someone local with MR2 experience to look at the car for you?

10-24-2007, 04:42 PM	#8 (permalink)
halo07 Freakin sweet Join Date: Sep 2007 Location: Huber Heights Posts: 181 Thanks: 10 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	i dont know anyone around dayton who has a mr2. i have seen like two mk1's in town but im always going the other direction and never get a chance to talk to them.